[3] He attended DeWitt Clinton High School in the Bronx, where he first developed an interest in acting while appearing in a student play.

Allan Arbus continued on as a solo photographer, but had given up the business to pursue an acting career by the time the couple divorced in 1969.

Arbus also starred opposite Bette Davis in Scream, Pretty Peggy (1973), and was featured as Gregory LaCava in W.C. Fields and Me (1976).

[11] These roles led to his casting as Maj. Sidney Freedman on M*A*S*H. His work on M*A*S*H helped his career as a character actor, and he eventually appeared in more than seventy TV shows and movies.

He appeared briefly in the 1973 film Cinderella Liberty as a drunken sailor; another 1973 film, Coffy (starring Pam Grier), featured Arbus as a drug dealer with strange sexual needs; in Damien - Omen II (1978), he played Pasarian, one of Damien's many victims in The Omen trilogy.