Her husband, Patrick Hogan, tells the Los Angeles Times that Mercer died April 27 of Alzheimer's disease complications in the Newbury Park area of Thousand Oaks, about 50 miles northwest of Los Angeles.
Besides her 1969 Broadway hit "Promises, Promises," Mercer won praise for the 1978 revival of "Stop the World, I Want to Get Off" co-starring Sammy Davis Jr.
On television, she starred in the ABC-TV comedy IT'S A LIVING from 1980 to 1982. She also had roles on ST. ELSEWHERE, MARY HARTMAN, MARY HARTMAN and PROVIDENCE.
She also memorably played Missy Hart, wife of Franklin Hart (Dabney Coleman) in the film 9 to 5.