Marguerite A. McAleer, 84, a resident of the Washington area for more than 49 years who was active in church organizations, died Thursday at Holy Cross Hospital. She had undergone heart surgery.

Mrs. McAleer, who was born in Philadelphia, lived in the Brookland section of Washington for many years and later in Riverdale and Kensington. She was a resident of Leafy House, an apartment complex for senior citizens in Silver Spring, at the time of her death.

She had been a member of the Sodality organizations at St. Catherine Laboure Catholic Church in Wheaton, at St. Anthony's Catholic Church in Brookland and at St. Bernard's Catholic Church in Riverdale. She also was a member of the Leisure Club at St. Catherine Laboure. In her earlier years, she took part in activities of the Grand Army of the Republic.

Her husband, Arthur F. McAleer, died in 1971.

Survivors include four sons, Charles A. and John H., both of Wheaton, Francis R., of Adelphi, and Gerald F., of Lanham; a daughter, Rita, of Kensington; 21 grandchildren, and 12 great-grandchildren.

The family suggests that expressions of sympathy be in the form of contributions in Mrs. McAleer's name to the Montgomery County Heart Fund, to the Montgomery County Cancer Society, or to a charity of one's choice.