HOLLYWOOD, Feb. 5— Sue Carol Ladd, an actress and widow of Alan Ladd, died Thursday of complications from a heart attack suffered two weeks ago, at the University of California Medical Center. She was 72 years old.

Mrs. Ladd, since her husband's death Jan. 29, 1964, from an accidental drug overdose, had been running family enterprises in Palm Springs, including the Elegant Gift Store, the Ladd Spanish Inn and Sue Carol Interior Decorating.

Born Evelyn Lederer in Chicago, Mrs. Ladd worked as an actress under the name of Sue Carol with Cecil B. De Mille and starred in ''Fox Follies'' and ''Girls Go Wild.'' She was also a member of the Wampas Girls.

She established her own talent agency, the Sue Carol Agency, and her major discovery was her husband, whom she met when he signed with her agency while he was a radio actor.

Surviving are two sons, David Ladd, an actor, and Alan Ladd Jr., president of the Ladd Company; two daughters, Alana Ladd, who is married to Michael Jackson, a radio talk-show host, and Carolle Veitch, who is married to John Veitch, Columbia Pictures productions president, and nine grandchildren.

Sue Ladd