MacGraw plays the role of Else, the matriarch of a rich family that is thrown when a family secret is revealed at a birthday party, the New York Daily News reported Tuesday.
"As the World Turns" veteran Larry Bryggman plays Else's husband in the play starting previews Thursday at the Music Box Theatre, while Michael Hayden, Julianna Margulies and Jeremy Sisto play her children.
MacGraw was Hollywood's "It Girl" of the 1970s and got an Oscar nomination for her weepy role opposite fellow nominee Ryan O'Neal for "Love Story."
She all but disappeared after the 1980s primetime soap "Dynasty," the newspaper noted.
"She came in and we were, like, 'Oh my God.' She's still beautiful," casting director Jim Carnahan told the News." My 29-year-old associate didn't really know who she was -- but her mother was positively thrilled."
Several experienced stage actresses read for the role, Carnahan said, but, "Ali came in and read just once -- and she sealed it."