T. Paul Mudd, 78, a retired Washington attorney and realtor who was active in church and civic groups, died Sunday at his home in Sacramento, Calif. He had had a series of strokes.

Mr. Mudd was born in Washington, the son and grandson of physicians. His grandfather was Dr. Samuel Alexander Mudd, who treated John Wilkes Booth after Booth had assassinated President Lincoln. Dr. Mudd was convicted of conspiracy to murder the President and was pardoned two years ago by President Carter.

Paul Mudd graduated from Gonzaga College High School and Georgetown University, where he was on the baseball, football and basketball teams. He earned his law degree at the old Columbus School of Law, now part of Catholic University. From the mid-1920s until 1943, he was a attorney in the Interior Department and then in the Department of Agriculture.

In 1943, he established a private law practice in Southeast Washington. He also engaged in the real estate business. He continued these activities until he retired in 1973 and moved to Sacramento. The firms begun by Mr. Mudd now are carried on by one of his sons, Richard Joseph Mudd of Alexandria.

Mr. Mudd, who lived in Southeast Ashington until about 1950 when he moved to Oxon Hill, was a member of the parish of St. Francis Xavier Catholic Church in Washington and was president of its Holy Name Society. He also was president of the Randal Highland Civic Association for many years and was an offical of the civil defense program in Southeast Washington during World War II.

In addition to Richard Joseph Mudd, Mr. Mudd's survivors include his wife, Francis Finotti Mudd of Sacramento; four other sons, Thomas Paul, Francis Finotti and Joseph Valentine, all of Sacramento, and John Philip, of Coral Gables, Fla.; one daughter, Mary Catherine Robey, of Manassas; a sister, Stella Kelley of Sacramento; a brother, Dr. Richard Dyer Mudd of Saginaw, Mich., and 21 grandchildren.