His films deal with controversial issues of social class, morality, and sexual taboos, combining the emotionally tortured characters of Ingmar Bergman with the avant garde style of the French New Wave.

Sjöman directed his first film in 1962, The Mistress ("Älskarinnan"), with a cast that included regular actors for Ingmar Bergman such as Bibi Andersson and Max von Sydow, showing a young woman in love with two men, one older and the other younger.

Sjöman's second film, 491, from 1964, is based on a novel by Lars Görling and deals with the issues of homosexuality and juvenile delinquency; it includes a scene in which a girl is raped, off-screen, by a dog.

"[5] The film also shows the protagonist's affair with a young man, played by Börje Ahlstedt, and sparked controversy both in Sweden and abroad because of its nudity and realistic scenes of sexual intercourse between the two lovers.

Rex Reed said the movie was "vile and disgusting" and Sjöman was "a very sick Swede with an overwhelming ego and a fondness for photographing pubic hair", but Norman Mailer described it as "one of the most important pictures I have ever seen in my life".

[6] An 11-minute section was cut by the British censor, and copies of the film were seized by U.S. Customs in January 1968 as obscene, and banned as pornography in most of the United States.