Henry Stewart McDonald, 86, a retired attorney at the Interior Department whose career in federal service included representing the interests of the Philippines here during World War II, died of pneumonia Aug. 29 at Northern Virginia Doctors' Hospital.

Mr. McDonald, who lived in Falls Church, was appointed legal adviser to the High Commissioner of the Philippines in 1941. He was en route to take up his post when the Japanese attacked Pearl Harbor -- and the Philippines -- on Dec. 7. He was recalled to Washington. His job for the rest of the war, when the islands were under Japanese occupation, was to represent the Philippines to the rest of the U.S. government.

After the war, he had a private law practice with the late Renah Camalier, once of a member of the old D.C. Commission that governed the city as an arm of Congress prior to Home Rule. About 1950, Mr. McDonald returned to the Interior Department. He retired there in 1973 as assistant to the undersecretary.

A native of Omaha, Mr. McDonald earned a law degree at the University of Nebraska and also studied at Harvard Law School. He served in the Army in World War I. He practiced law in New York City and helped draft some early federal legislation governing commercial aviation.

In 1934, he moved to Washington as an attorney with the old National Recovery Administration. He later worked for the Agriculture and Treasury departments and then Interior.

Mr. McDonald was a past president and life member of the University Club, a life member of the Columbia Country Club and a member of the Congressional Country Club. He was an usher and an elder of the National Presbyterian Church.

His wife of 53 years, Beatrice McDonald, died in 1974. Survivors include four children, H. Stewart McDonald III of Tampa, Fla., Nancy McDonald Beyer of Falls Church, Dr. Duncan Keith McDonald of Salt Lake City, and Kate McDonald Hathaway of St. Louis; 11 grandchildren, and nine great-grandchildren