The US Marine Corps has the most stable and most recognizable uniforms in the American military; the Blue Dress dates back to the early 19th century and the service uniform to the early 20th century. Marines' uniforms are also distinct in their simplicity; Marines do not wear unit patches or United States flags on any of their uniforms, nor name tags on their service and formal uniforms. Only a handful of skills (parachutist, air crew, explosive ordnance disposal, etc.) warrant distinguishing badges, and rank insignia is not worn on uniform headgear (with the exception of an officer's garrison service cover). While other servicemembers commonly identify with a sub-group as much as or more than their service (Ranger, submariner, aircrew, etc.), Marine uniforms do not reflect such division.

Marines have three main uniforms: Dress, Service, and Utility. The Marine Corps Dress uniform is the most elaborate, worn for formal or ceremonial occasions. There are three different forms of the Dress uniform, the most common being the Blue Dress Uniform, also called "Dress Blues" or simply "Blues". It is most often seen in recruiting advertisements and is equivalent to black tie. There is also a "Blue-White" Dress for summer, and Evening Dress for formal (white tie) occasions. Versions with a khaki shirt in lieu of the coat are worn as a daily working uniform by Marine recruiters.

The Service Uniform was once the prescribed daily work attire in garrison; however, it has been largely superseded in this role by the utility uniform. Consisting of olive green and khaki colors, it is commonly referred to as "Greens". It is roughly equivalent in function and composition to a business suit.

The Utility Uniform, currently the Marine Corps Combat Utility Uniform, is a camouflage uniform intended for wear in the field or for dirty work in garrison, though it has now been standardized for regular duty. It is rendered in a distinctive MARPAT pixelated camouflage (sometimes referred to as digitals or digies) that breaks up the wearer's shape, and also serves to distinguish Marine uniforms from those of other services. In garrison, the woodland uniform is worn sleeves down in winter, and the desert uniform is worn with sleeves rolled up in summer. The sleeves are rolled tightly to the biceps, exposing the lighter inside layer, and forming a neat cuff to present a crisper appearance to the otherwise formless uniform. In years past when Marines wore identical utilities to their Army and Air Force counterparts, this served to distinguish them as the other services have a different practice for rolling sleeves. Marines consider the utilities a working uniform and do not permit their wear off-base, except in transit to and from their place of duty and in the event of an emergency. This, too, distinguishes them from other services, which have less stringent restrictions.

US Marine Corps Dress uniform

The Marine Corps dress uniform is an elaborate uniform worn for formal or ceremonial occasions. Its basic form of a blue jacket with red trim dates back to the 19th century. It is the only U.S. military uniform that incorporates all three colors of the U.S. Flag. There are three different variations of the Dress uniform: Evening Dress, Blue Dress, and Blue-White Dress; only officers and SNCOs are authorized to wear the Evening Dress. Until 2000, there was a White Dress uniform, similar in appearance to the U.S. Navy's Dress White uniforms, but worn by officers only (in a manner similar to that of the Dress White uniforms worn in the U.S. Coast Guard). This uniform has since been replaced with the Blue/White Dress uniform for officers and SNCOs.

Blue Dress

The most recognizable uniform of the Marine Corps is the Blue Dress uniform, often seen in recruiting advertisements. It is often called "Dress Blues" or simply "Blues". It is equivalent in composition and use to civilian black tie. The various designations are listed in descending order of formality:

• Blue Dress "A" has a long-sleeved midnight blue coat (enlisted members have red trim) with a standing collar and belt (white web belt and gold waistplate for enlisted; midnight blue for officers with a gold M-buckle), white barracks cover (a peaked cap), plain white shirt, sky blue trousers (midnight blue for general officers), white gloves, and black dress shoes and socks. Full-size medals are worn on the left chest, with ribbon-only awards worn on the right. Marksmanship badges are not worn. Women wear pumps in place of shoes, and may wear a skirt in place of slacks. For men, the dress coat is cut to be formfitting.
• Blue Dress "B" is the same as "A", but medals are replaced with their corresponding ribbons and all are consolidated on the left chest. Marksmanship badges may be worn.
• Blue Dress "C" is the same as "B", but a khaki long sleeve button-up shirt and tie replace the outer blue coat and white gloves. Ribbons and badges are normally worn on the shirt.
• Blue Dress "D" is the same as "C", but with a khaki short sleeve button-up shirt and no tie.

Because the Blue Dress uniform is considered formal wear, Blue Dress "C" and "D" are rarely worn. The main exception are Marine Recruiters and Marine Corps Security Guards, who wear the "C" and "D" in warm weather. Only the "B", "C", and "D" Blue Dress uniforms are authorized for leave and liberty wear; the "A" is not.

Officers, NCOs, and SNCOs wear a scarlet "blood stripe" down the outer seam of each leg of the blue trousers. General officers wear a 2 in (5.1 cm) wide stripe, field- and company-grade officers have a 1.5 in (3.8 cm) wide stripe, SNCOs and NCOs have a 1.125 in (2.86 cm) wide stripe. General officers wear trousers that are the same color as the coat, while all other ranks wear medium (sky) blue trousers. A blue boatcloak with a scarlet lining is optional.

A blue crewneck sweater, in the same color shade as that of the trousers, may be worn with the "C" and "D" uniforms, in which case rank insignia will continue to be worn on the collar by officers, and all wearers will display rank insignia on shoulder epaulettes (polished brass for enlisted). The collar is worn on the outside of the sweater in order to display the rated rank insignia of officers. When wearing the crewneck sweater with the long sleeve khaki shirt, a tie is not required.

Blue-White Dress

Prior to 1998, the "Blue-White" dress uniform was authorized to be worn for the ceremonial units at Marine Barracks, 8th & I in Washington, D.C. (most famously the Silent Drill Platoon and Color guard). Since then, it has become the authorized summer dress uniform for all officers (it replaced, in 2000, an all-white uniform, similar in appearance to that of the Naval Officer/CPO white dress uniform), SNCOs (unless they are in formation with NCOs and junior enlisted personnel who are not authorized to wear the uniform), and by NCOs and junior enlisted personnel for ceremonies and social events only, if authorized and provided by the command structure.

Like the Blue Dress uniform, the Blue-White Dress consists of an "A" and "B" uniform, and is worn in the same manner as that of the Blue Dress uniform, except for the trousers, skirt, or slacks being white instead of blue. Unlike the Dress Blues, the Blue-White Dress uniforms do not feature the "blood stripe". As with the Dress Blues, the "A" is not authorized for leave and liberty wear. The white trousers are not authorized for wear with either the long-sleeved or the short-sleeved khaki shirt, precluding the "C" and "D" uniforms.

Red Dress

To differentiate themselves from the infantry, musicians—at that time, merely buglers and signal callers—would reverse the traditional colors. Today's Marine Corps musicians still carry on this tradition by wearing a scarlet blouse with blue trim instead of the Dress Blues blouse. Currently, the Red-Dress uniform is worn only by members of the United States Marine Band and the United States Marine Drum and Bugle Corps, both based in Washington, D.C.; members of the twelve fleet bands wear standard Marine uniforms.

Like the Blue-White Dress uniform, musicians are not authorized to wear the khaki shirts with the Red-Dress uniform. Should the condition warrant (e.g., summer heat), the band will wear the appropriate Dress or Service uniforms.

Evening Dress

The Evening Dress is the most formal (and by U.S. Military standards, the most elaborate) of the Dress uniforms, and is the equivalent of white tie in usage. It is only authorized for wear by officers and SNCOs, and only a required uniform item for senior officers (Majors and above). It comes in three varieties:

• Evening dress "A" (for officers) is similar to Dress Blue "A", except an evening coat with strip collar, white waistcoat, and white shirt with pique placket is worn. The stripe on the trousers is a thin red stripe inside a gold embroidered stripe. Women wear a long skirt. Miniature medals and badges are worn.
• Evening dress "B" is identical to Evening Dress "A" except men wear a scarlet waistcoat (General officers) or cummerbund (other officers), and women may wear a short skirt.
• SNCO Evening Dress for Staff Non-Commissioned Officers, and much resembles a tuxedo with historic 1890s-era rank insignia sewn on the sleeves.

A blue boatcloak with a scarlet silk liner is optional. Junior officers not required to possess Evening Dress may substitute Blue or Blue-White dress "A". It is appropriate for such occasions as State functions, inaugural receptions and dinners, and formal dinners.

US Marine Corps Service uniform

The service uniform consists of green and khaki colors. It is roughly equivalent in function and composition to a business suit. It is the prescribed uniform when

• serving on a court-martial
• making official visits and calls on American and foreign dignitaries, officials, and military officers.
• visiting the White House, except when in a tourist capacity, or on an occasion where another uniform is specified.
• reporting for duty onshore

Like the Blue Dress uniform, the service uniform is authorized for wear while off-duty (i.e., while on leave or liberty).

The service uniforms are designated:

• Service "A" (or Alpha) is the base uniform. It consists of a green coat, green trousers with khaki web belt, khaki long-sleeve button-up shirt, khaki tie, tie clasp, and black shoes. The coat is cut to be semi-form fitting, with ribbons and marksmanship badges worn on the left chest of the coat. Women wear a green necktab in place of the tie, pumps instead of shoes, and have the option of wearing a skirt instead of slacks. It is sometimes appropriate to remove the jacket while indoors.
• Service "B" (or Bravo) is identical to the "A" except the coat is removed. Ribbons may be worn on the shirt.
• Service "C" (or Charlie) is identical to the "B" except with a short-sleeve button-up shirt and no tie.

There are two types of authorized headwear for the service uniform. Both men and women may wear the green soft garrison cap, sometimes nicknamed a "piss cutter". There is the option of wearing a hard-framed service cap (called a Barracks Cover). The design of these covers differ between women and men. As on the Blue Dress uniform, officers wear rank insignia on the shoulder epaulettes of their jackets and the collars of their shirts, while enlisted personnel wear rank insignia sewn on their sleeves.

A green crewneck sweater may be worn with the "B" and "C" uniforms, in which case rank insignia will continue to be worn on the collar by officers and all ranks will wear rank insignia on shoulder epaulettes (black for enlisted). The collar is worn on the outside of the sweater in order to display the rated rank insignia of officers. When wearing the crewneck sweater with the long sleeve khaki shirt, a tie is not required.

US Marine Corps Utility uniform

The Marine Corps Combat Utility Uniform or MCCUU is intended for wear in the field or for working parties, but has become the typical working uniform for all deployed and most garrison Marines and Sailors. It is rendered in MARPAT digital camouflage that breaks up the wearer's shape, and also serves to distinguish Marine uniforms from those of other services. Previously, Marines wore the same utility uniforms as the Army. It consists of MARPAT blouse and trousers, green undershirt, and tan (specifically "olive mojave") suede boots. There are two approved varieties of MARPAT, woodland/winter (green/brown/black) and desert/summer (tan/brown/grey). To further distinguish the uniform, upon close examination, the Eagle, Globe, and Anchor can be found within the pattern.

The variety worn depends on the environment and season: Deployed Marines wear whichever color is more appropriate to the climate and terrain, Marines in garrison wear the woodland MCCUU with long sleeves in winter months, and the desert MCCUU with sleeves rolled up in summer months (the transition occurs simultaneously with Daylight Saving Time). When rolled, the sleeves of the blouse are tightly folded up to the biceps, exposing the lighter inside layer, and forming a neat cuff to present a crisper appearance to the otherwise formless uniform. In the past, when Marines wore the same utilities as the Army and Air Force, this served to distinguish them from the other branches, who folded the sleeves in with the camo facing out. In Haiti, the practice earned them the nickname "whitesleeves".

Both officers and enlisted wear rank insignia on each collar, which is affixed like a pin and not sewn on as in the Army/Air Force. Enlisted insignia is always black, while officers wear bright metal insignia in garrison and subdued insignia (or none at all) in the field. Most badges and breast insignia are authorized for wear on the utility uniform, shined or subdued as appropriate. Landing Support Marines also wear the Red Patch insignia.

Unlike the dress and service uniforms, utility uniforms are not permitted for wear on leave or liberty (i.e., while off-duty), except when traveling in a vehicle between a place of duty and a residence, or in emergency stops.

The approved headwear is the utility cover, an eight-pointed brimmed hat that is worn "blocked", that is, creased and peaked. In the field, a boonie cover is also authorized. The trouser legs are "bloused", or the cuffs are rolled inside and tightened over their boots with a spring or elastic band known as a "boot band" or "blousing garter". With the introduction of the Marine Corps Martial Arts Program (MCMAP), Marines now wear color-coded rigger's belts instead of the old web belt, indicating their level of proficiency in MCMAP (the web belt was phased out in 2008 due to a requirement for all Marines to achieve a tan belt rank by then).

In combat, Marines will also wear one of two ballistic vests: the Outer Tactical Vest and the newer Modular Tactical Vest, as well as the Lightweight Helmet (replacing the PASGT helmet) and Improved Load Bearing Equipment. Marines in a combat area may also wear Flame resistant organizational gear, or FROG uniforms. These combat uniforms are designed to reduce fire-related injuries, and look quite similar to the MCCUU. Other individual equipment may be worn as directed.

The wearing of the MCCUU by civilian contractors deploying with Marine units was granted early in the Iraq War, but rescinded in early 2008.

US Marine Corps Physical training uniform

The Physical training uniform or PT uniform consists of one of the following pairs:

• green nylon shorts and cotton t-shirt (shirts with unit logos can be authorized)
• green sweatpants and sweatshirt with the Marine Corps emblem printed in black on the left chest and thigh
• The green tracksuit with gold and scarlet "Marines" lettering and reflective trim was unveiled during a tour of Iraq in December 2007, by Commandant of the Marine Corps General James Conway. It began to be issued to Marines free of charge in February 2008 and will be mandatory possession by the end of FY 2010.

In addition, Marines can wear a watch cap and gloves in cold weather, or a hydration pack to prevent dehydration.