Dorothy E. Irelan, 69, a retired administrative assistant in the construction engineering branch of the National Institutes of Health who was active in church and civic affairs, died Dec. 19 at her home at Rossmoor Leisure World in Silver Spring. She had cancer.

Mrs. Irelan, who was born in the Georgetown section of Washington, was a graduate of Roosevelt High School and later attended George Washington University. In the early 1940s, she worked for the Republican National Committee.

She began her career at NIH in 1958. She first was an administrative assistant in the research facilities planning branch, where many of her duties concerned personnel. She was at NIH during a period of major expansion of research laboratories and other facilities. At the time of her retirement in 1973, she was an administrative assistant in the agency's construction engineering branch.

Mrs. Irelan was a member of the Oakdale Emory United Methodist Church in Olney and in 1978 was honored with a life membership in the United Methodist Women. She also did volunteer work at Montgomery General Hospital. At Rossmoor, she was secretary of the Kiwanis Wives Club.

Her first husband, James E. White, died in 1971.

Survivors include her husband, James Kennedy Irelan of Rossmoor Leisure World; a daughter, Jane F. Buswell of Silver Spring; a brother, George M. Shertzer of Bethesda, and two grandchildren.