At the 4077th Mobile Army Surgical Hospital (M.A.S.H) unit in Korea, two army doctors by the names of Hawkeye Pierce and Trapper John McIntyre receive some exciting news in the mail. Their Korean house boy, Ho-John got accepted into Hawkeye's old college. Hawkeye and Trapper decide to hold a party filled with music, dancing, and alcohol to raise money for Ho-John's plane trip to the U.S. They achieve this by raffling off a weekend pass with a nurse, Lieutenant Dish for R&R in Tokyo.

Trapper and Hawkeye seek to keep a new nurse from being transferred by Hot Lips, and they vie for her affection. Henry Blake, challenged by another commander to a boxing tournament, makes Trapper fight a big, intimidating soldier in exchange for keeping the nurse at the 4077th. Hawkeye and Ugly John employ the use of a glove soaked with ether to insure Trapper's victory, which impresses the nurse. Margaret and Frank's attempts to unfix the match collapses, as they are flattened by the unconscious boxer!

The 4077th is designated as the setting for the making of an army film on Mobile Army Surgical Hospital units. Hawkeye is chosen as the star while Margaret and Frank compose a screenplay. The Eye Of The Hawk objects to the piece of propaganda that filmmaker Lt. Bricker is producing and, having exposed the original film, reshoots a new one his way, starring himself as Groucho Marx-ish Yankee Doodle Doctor, and poking fun at glorifying doctors while concluding with a rather serious speech about the hell of war.

Henry receives a citation for the camp achieving the best efficiency rating, and then General Hammond reassigns him to Tokyo. Frank then changes the camp to be more military, and he confiscates Hawkeye's and Trapper's still. They use forged passes to go to Tokyo to convince Henry to come back and end up pretending Radar is sick.

A rash of thefts breaks out in the camp. Missing pieces include Frank's silver picture frame, Margaret's hair brush, and Trapper's watch. The camp is searched and everything is found in Hawkeye's locker. Everyone thinks he did it. Hawkeye manages to announce to the camp that the items will be dusted for prints to identify the real thief, and catches Ho-Jon. He needed money to bring his family from the North, and to bribe border guards.

Hawkeye moves a wounded North Korean soldier into The Swamp, rather than let him be shipped out before he's stable. During the night he and Trapper play Dracula, and siphon off a pint of Frank's blood. The soldier then contracts hepatitis, so they have to test Frank without him knowing, and have to keep him away from Margaret and the patients.

The nurses go to extremes lengths to find a date for Nurse Eddie - they won't go out with anyone until Eddie gets a date. The men draw straws, and Hawkeye is the big loser, especially after Eddie nearly kills him in a scene resembling teenage "mating" rituals.

Radar gets a Dear John recording from home. Hawkeye and Trapper try to set him up with a date, but fail. Radar is taken by a new nurse at the camp and she is into poetry and music, so they coach him. Margaret wants to stop the relationship, so Hawkeye and Trapper get between her and Frank until she relents. Radar's "Ahhhh, Bach!" and "That's highly significant," quotes win him the girl.

Hawkeye and Trapper operate on a famous Colonel - after discovering that he is particularly ruthless about sacrificing his men, they come up with a scheme to get him sent back to the states with a little unwitting help from Frank, Margaret, and a drunk Henry.

Frank throws his back out whilst spending the evening with Margaret, and ends up in traction. He promptly applies for the Purple Heart, having been 'technically' wounded at a frontline unit. Tommy Gillis, an old friend of Hawkeye's, is writing a book about the war, and pays him a visit. Later, Tommy is brought into the camp, seriously wounded, and Hawkeye can't save him. A 15-year-old kid is in the hospital to have his appendix out. He joined up to be a hero back home, but Hawkeye has him sent home, giving him Frank's purple heart.

The camp tunes into the Army/Navy football game, only to be shelled and have an unexploded bomb land in the middle of the compound. They ring around trying to identify the bomb, and the camp prepares for the worst. Hawkeye and Trapper are left the task of following instructions to disarm the bomb, which turns out to be full of propaganda leaflets from the CIA.

Hawkeye and Frank argue over Frank's surgical ability. Hawkeye performs a difficult operation and the patient does not recover, as he should. Hawkeye begins to doubt his ability and moves out of The Swamp. He decides to open up his patients again, and discovers a nick in the colon that even Frank admits anyone could have missed.

Captain Kaplan is to be shipped home, but becomes paranoid that something will happen to him before he leaves. He takes the wheel of the jeep to drive to Kimpo himself, but crashes and ends up in plaster. Henry's wife is in labor and gives birth while he has Radar calling the hospital every 5 mins.An entertainer, Jackie Flash, visits the camp to entertain the troops.

Gen. Clayton sends a psychiatrist to the 4077th to gauge the camp's cohesiveness and fitness as a unit.

An inept, if punctual, bomber pilot provides comic relief for Hawkeye and Trapper, but inspires Frank to call out the heavy artillery.

Radar chronicles the antics of a typical week at the 4077th, which includes Hawkeye falling for a new nurse, a POW going berserk in the OR and Klinger seeking a psychiatric discharge.

Hawkeye and Trapper receive high-level flak when they buck the brass to report the "friendly fire" shelling of a South Korean village.

Hawkeye has been operating so long he just can't quit, and he decides to try to end the war while he's at it.

Everyone wants to mother a wounded and apparently orphaned boy.

Hawkeye cuts through red tape to help a GI marry his child's Korean mother, and cuts romantic ties with a bigoted nurse.

Henry's fitness for command is called into question when he's put on trial for charges stemming from the tomfoolery at the 4077th.

Another letter from Hawkeye to his father tells about a bigoted soldier who wants the "right color" blood, a live grenade in the OR and Henry's home movies.

A lone sniper turns the hospital compound into a combat zone, traps Henry and Radar in the showers and forces surgery by candlelight after he knocks out the generator.

A flu epidemic leaves yet-to-be infected Hawkeye and Margaret more overworked than ever.

Hawkeye and Trapper hassle the brass to obtain a vital piece of medical equipment.

The 4077th and friends convene for their weekly “Medical Conference,” A.K.A. Poker while Radar runs over a civilian and Frank is held hostage in the showers by an enlisted man.

Depressed by news from home, Margaret examines her life and decides to request a transfer.

Something smells rank at the 4077th, and it might be the new officers' club--from which enlisted types are barred.

Henry returns from Tokyo in love with a woman half his age, but he seems to have forgotten one thing--he's married.

Hawkeye's quest for new boots turns into a never-ending game of horse trading.

A private with a prominent proboscis pleads for prohibited plastic surgery--but Frank and Margaret smell a rat.

A local farmer claims the 4077th is on his land, and a Korean woman claims Radar is the father of her child.

Frank chooses a lull in the action to ask Hawkeye and Trapper to perform his hernia operation, and that's just when the war returns full tilt.

The MASH 4077 is visted by General Steele. He wishes to move the camp 5 miles down the road. Hawkeye and Henry are charged with mutiny. And Hawkeye is also charged with impersonating a reporter.

Psychiatrist Sidney Freedman composes a letter to Sigmund Freud during a visit to the 4077, while the rest of the camp endures the hijinks of a mystery prankster.

With the arrival of a shipment of records, Radar plays the part of a disc jockey and helps to get everyone through the incredibly long deluge of wounded.