The 4077th MASH is a typical U.S. Army Mobile Army Surgical Hospital during the Korean War. Based on a concept that evolved soon after the Second World War, these units are designed to be highly mobile, with its own transportation to allow them to keep up with advancing troops or "bug out" in the face of oncoming enemy threats. They therefore operated mainly out of tents or used whatever temporary buildings they could find.
For most of the TV series, the 4077th MASH was located near the Korean town of Uijeongbu. The major feature in the camp compound was the hospital building (which in the case of the 4077th) was a T-shaped wooden structure. The hospital building included the pre-op ward, the O.R., and the post-op ward), as well as the scrub room, pharmacy, lab and X-ray room. These rooms took up two long arms of the "T". Also attached to the hospital building was the unit headquarters and the commander's office.
Nearby are the commander's tent, and the Swamp. Across from the hospital building are the main accommodation facilities: the mess tent and kitchen, the head nurse's tent, the Chaplain's tent, the V.I.P. tent, one or several nurses' tents, and enlisted tents. Klinger, it seems, also had his own tent. Nearby are the shower tent, the latrine, the laundry tent and a barber tent.
Occasionally, a dental clinic and an optometrist facility can be seen but it is assumed that these are itinerant services provided by specialists who traveled from unit to unit wherever they are needed. Landmarks around the 4077th MASH include Rosie's Bar and the minefield.
- Lt. Col. Henry Braymore Blake (novels, movie, TV series)
- Col. Sherman T. Potter (TV series only)
- Maj. Frank Burns (in the absence of Lt. Col. Blake or Col. Potter) (appeared in novels, movie, and TV series, but only assumed command in TV series)
- Maj. Charles Emerson Winchester III (in the absence of Col. Potter after replacing Burns) (TV series only)
- Capt. Benjamin Franklin "Hawkeye" Pierce(as Chief Surgeon, during the absence of Col. Potter, while Maj. Winchester was ill or too involved in a case) (TV Series only)
- Maj. Margaret Houlihan (in "Carry On, Hawkeye" when everyone is sick including commanding officer Colonel Blake, Margaret took command temporarily)