Who sang suicide is painless?

"Suicide Is Painless" is a song written by Johnny Mandel (music) and Mike Altman (lyrics), which is best known for being featured as the theme song for both the movie and TV series M*A*S*H. The actual title is "Song from M*A*S*H" (Suicide is Painless)".

The song is played during the film's opening credits, sung by uncredited session singers John Bahler,Tom Bahler, Ron Hicklinand Ian Freebairn-Smith (the vocals are sometimes misattributed to Johnny Mandel, due to his being the only name officially credited for the song).