Ralph H. Marlatt, 68, a former union leader and congressional aide, died Tuesday in Sanger, Calif., after a stroke.

He first served on Capitol Hill in 1949 as administrative assistant to Rep. Cecil White, D-Calif. During the Korean war, he worked for the Defense Department.

Mr. Marlatt returned to Capitol Hill in the early 1950s as administrative assistant to rep. Walter Judd (RMinn.). He later held similar positions with Reps. Oliver Bolton (R-Ohio), Henry Talle (R-Iowa), Bruce Alger (R-Tex.), James Martin (R-Ala.) and Dan Kuykendall (R-Tenn.). He retired from the latter's staff in 1971.

Born in Peru, Ind., Mr. Marlatt joined the assembly line of the Ford Motor Co. in Detroit in the early 1930s, and worked actively with the late Walter Reuther in the United Auto Workers.

Later, he moved to Flint, Mich., where he became editor of the Flint weekly, a UAW publication. At this time, he became a close friend of the late John L. Lewis, who was then organizing dairy farmers.

Mr. Marlatt became national director of the United Dairy Farmers and came here in 1942. He left the dairy union two years later and returned to Flint to run for Congress.

After losing the primary election, Mr. Marlatt moved to Sanger, where he became editor of the Sanger Herald. He remained there until 1949.

In Washington, he was active in the Congressional Secretaries Club and helped organize the Capitol Hill Players. He served as president of the Men of St. John's College High School here in 1954 and 1955.

Shortly after he retired as a Hill aide, Mr. Marlatt became an official in the administration of Gov. Winfield Dunn of Tennessee. He retired a second time in 1974, and moved to California.

He is survived by his wife, Kathleen Mahoney Marlatt, of the home in Sanger; a son, Ralph J., of Annandale; a sister, Mable Kimbel, of Hasahan, S.C., and two grandchildren.