Dennis Collins, 65, a Washington attorney for 40 years who was active in church and youth work, died of cancer Saturday at his home in Washington.

Mr. Collins left his home in Abbeyfeale, Ireland, when he was 17 to join an older brother and sister in Washington.

After graduating from Western High School in 1934, he worked as a busboy, window washer and clerk. He became interested in law while making sandwiches at Greene's, a delicatessen on 6th and D streets NW frequented by lawyers and judges.

"Many a judge has told me I was a better sandwich maker than a lawyer," he would frequently joke. Mr. Collins earned a law degree at Columbus Law School in 1940 and joined the law office of Neil Burkinshaw. He leaves two partners, William Fitzgerald and Jerry Collins.

"I knew Dennis Collins as an opponent and as a judge," said D.C. Superior Judge Paul McArdle. "As an opponent I was completely at a disadvantage because I didn't have that Irish brogue which he cultivated so beautifully," McArdle said.

Mr. Collins was a member of the Holy Name Society, the Serra Club and the Ancient Order of Hibernians. He was president of the Nativity Elementary School Catholic Yough Organization sports program for 27 years. For most of these years, he would charter a boat on the Chesapeake Bay to take the grade school athletes on a fishing trip.

He is survived by his wife, Mary, of the home; two daughters, Mary Margaret Nicholaus of Silver Spring, and Angela Collins of Ashburn, Va.; four sons, Kevin of Bethesda, Joseph of Aldie, Va., and Denis and Brendan, both of Washington; a brother, Dan, of Ireland; four sisters, Nora Kelly, of Greenbelt, and Mary McGuire, Shelia Richardson, and Kathleen Stuart, all of Arlington, and two grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to HAP Program at Gonzaga College High School in Washington or Christendom College, Rte. 3, Front Royal, Va. 22630.