A Moon for the Misbegotten, produced in 1947, was written by O'Neill as a eulogy for his brother, Jamie, who is fictionalized as Jamie Tyrone in the play. As he is in Long Day's Journey into Night, Jamie is an alcoholic who seeks solace in the arms of a series of large women. The play deals with his hapless affair with Josie Hogan. It was a work that O'Neill finally came to loathe, possibly because his own son followed in his uncle's footsteps and committed suicide.

Trouble in the Flesh (1959), is Max Wylie's graphic fictional account of Seton Farrier, whose life as the greatest dramatist of his day is clearly based on O'Neill's biography.

East of Eden (1952), John Steinbeck's fictional saga of the Trask family investigates themes parallel to those treated in Long Day's Journey into Night. Based on the biblical story of Cain and Abel, the novel focuses on family depravity, sibling jealousy and rivalry, guilt, and forgiveness.

Death of a Salesman (1949), Arthur Miller's great "tragedy of the common man," has some parallels with O'Neill's play, including the tragic consequences of material pursuits and the alienation of sons from their father. Miller's play is the principal rival claimant to Long Day's Journey into Night as America's greatest tragedy.

Buried Child (1978), Sam Shepard's mythic study of a dysfunctional family riddled with guilt for the murder of a real or illusory child, with some parallels to O'Neill's Long Day's Journey into Night in its themes and retrospective method.

A Hatful of Rain (1955), Michael V. Gazzo's play dealing with the impact of a veteran's drug addiction on the lives of his wife, father, and brother has thematic parallels to O'Neill's work. An excellent 1957 film version won Anthony Franciosa an Academy Award nomination for best actor.