William S.Hepner, Sr., 90, an official with the American Red Cross for 35 years before retiring in 1954, died of cardiac arrest Friday at Suburban Hospital in Bethesda.

Mr. Hepner joined the Red Cross in 1923 and was southern division war services director in Atlanta before coming to national headquarters here two years later. He had served in the Army during World War I.

During World War Ii, he was promoted to national director of the old Military and Naval Welfare Service of the Red Cross. He was asistant administrator of service to the armed forces at the time he retired.

He was a native of Cedar Rapids, Iowa, and a graduate of Cornell College in Mount Vernon, Iowa. He had lived in Bethesda for the past 51 years.

A member of the Arts Club of Washington since 1929, Mr. Hepner had served on its board of directors and was a past president. He also was a member of Bethesda Presbysterian Church.

His wife, Clara died in 1965. Mr. Hepner is survived by two sons William S. Jr., of Derwood, Md., and Richard ., of New Ipswich, N.H.; a sister, Regina Lancaster of Cedar Rapids, and nine grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the American Red Cross.