Robert Ruben, 58, who retired in January as the administrative assistant to Rep. James Corman (D-Calif.) after 12 years of service, died Monday at his home in Chevy Chase. He had amyotrophic lateral sclerosis, which is also known as Lou Gehrig's disease.

Mr. Ruben, who was born in Los Angeles, attended the University of Oregon. During World War II, he was commissioned in the Navy and served in the Pacific. After the war, he returned to Los Angeles, where he was a television cameraman for the National Broadcasting Company.

In 1962, he moved to Washington and became director for radio and television in the public affairs office of the Peace Corps. In 1964, he was named associate director of the Partners of the Alliance for Progress in the Agency for International Development. He remained there until joining Corman's staff.

Mr. Ruben is survived by his wife of 35 years, Margit, of Chevy Chase; two children, Katherine Ruben of Philadelphia, and Peter, of Saskatchewan, Canada; his mother, Mrs. William Morris of Los Angeles; one brother, Albert, of New York City, and one grandchild.

The family suggests that expressions of sympathy be in the form of contributions to the ALS Society of America, Studio City, Calif., or to the Muscular Dystrophy Association, 1800 Massachusetts Ave. NW, Washington, D.C.