Dorothy Mallery (Mal) Corcoran, 52, a former choir director at St. Raphael's Catholic Church in Potomac and a singer and pianist at various Washington area clubs, died Monday at Suburban Hospital in Bethesda. She had multiple sclerosis.

Mrs. Corcoran, who lived in Potomac, directed the choir at St. Raphael's for several years until about 1977, when she retired for reasons of health. Failing health also ended her career as a singer and pianist.

She was born in Minneapolis and graduated from Gustavus Adolphus College in St. Peter, Minn. She later was a music teacher in public schools in Wheaton, Minn., and in St. Paul and Minneapolis. She also sand and played in cabarets in those cities.

Mrs. Corcoran was active in Democratic politics and was a volunteer in the presidential campaigns of John F. Kennedy in 1960 and Lyndon B. Johnson in 1964.

Mrs. Corcoran and her family moved from Minneapolis to Bethesda in 1965 when her husband, Lee Corcoran, joined the Small Business Administration. They later moved to Potomac.

In addition to her husband, of Potomac, survivors include five children, Thomas Lee, Mary Margaret, James Eugene, Carol Ann and Constance Lou, all of Potomac; her mother, Mary Mallery of Hopkins, Minn., and two sisters, Mary Houlberg of Kalispell, Mont., and Billie Kadlec of Hopkins. Another son, Willilam Patrick, died 10 years ago.