The film starred Richard Benjamin, Karen Black and Lee Grant, with Jack Somack, Jeannie Berlin and Jill Clayburgh in supporting roles.

During a session with his psychoanalyst (who never speaks during the film), he explores his childhood, his relationship with his overbearing mother, his sexual fantasies and desires, his problems with women, and his obsession with his own religion.

Via flashbacks, we learn about his affairs with Bubbles Girardi, the daughter of a local hoodlum; leftist Israeli Naomi, whom he attempts to rape; and gentile Mary Jane Reid, whose nickname "Monkey" reflects her remarkable agility at achieving a variety of sexual positions.

Mary Jane seemingly is the girl of Portnoy's dreams, but as their relationship deepens and she begins to pressure him into giving her a ring, he shrinks from making a permanent commitment to her.

Besides adapting the Philip Roth novel into a lucid, balanced and moral screenplay, and producing handsomely on various locations, Ernest Lehman makes an excellent directorial debut.