Yvonne Beaubian Williamson, 48, a retired speech therapist for the District of Columbia public school system, died Thursday at the Washington Hospital Center. She suffered from a heart ailment.

Mrs. Williamson began her career in education teaching English at Taft Junior High School here. After special training in speech and audiology, she worked as a speech therapist at the Shepherd, Powell, Noyes, Ketcham, Orr and Garfield elemtary schools here until her retirement Oct. 31 because of failing health.

Before teaching, Mrs. Williamson had worked for the U.S. Bureau of the Census and the D.C. birth and death records division.

A native of Washington, she earned a bachelor's degree from West Virginia State College. She also did postgraduate work at the University of Maryland and attended the old D.C. Teachers College.

Mrs. Williamson was an executive board member of the Washington Teachers Union and served as the first chairman of the School Chapter Advisory Committee for speech therapists.She also was a past president of the Langdon Elementary School PTA and a former member of the D.C. Central Labor Council.

Survivors include her hasband, Lynwood; two daughters, Lynne C. and Leslie B.; and one son, Wendell W., all of the home in Washington; and her father and stepmother, John O. and Fredryka Beaubian, also of Washington.