Starting in 1972, Swit played the lusty, extremely capable head nurse Major Margaret "Hot Lips" Houlihan in the television series "M*A*S*H", a comedy set in US Army mobile field hospital during the Korean War. Swit inherited the star-making role from actress Sally Kellerman, who portrayed Houlihan in the feature film. In the first few seasons her character was single and blindly patriotic, and she had no friends among the camp surgeons and nurses, with the notable exception of her married lover, Major Frank Burns, portrayed by Larry Linville. Over time her character was considerably softened. She married a lieutenant-colonel but divorced soon after. She became good friends with her fellow officers, and her attitude towards the Koreans in and around the camp became more enlightened. The change reflected that of the series in general, from absurdist dark humor to mature comedy-drama. Swit was one of only four cast members to stay for all 11 seasons of the show, from 1972 to 1983 (the others are Alan Alda, Jamie Farr, and William Christopher).