Thomas F. Ryan, 28, law clerk to U.S. District Judge John Lewis Smith Jr., died Thursday at Suburban Hospital in Bethesda of injuries suffered in an automabile accident last Saturday.

Mr. Ryan was a graduate of Georgetown University and Georgetown University Law School. He had been Judge Smith's law clerk since August, 1976, and had worked on several major cases involving last week's ruling on government ownership of former Secretary of State Henry Kissinger's taped telephone transcripts.

A native of Evansville. Ind. Mr. Ryan was a pilot and a former amateartennis champion. He was captain of the Georgetown tennis team in 1970 and 1971.

He was admitted to the begin Maryland last January, and was a member of the Maryland and American Bar associations.

Mr. Ryan is survived by his wife, the former Christmas Coffey and two children. Thomas and Maryland of the home in Bethesda his parents, Mr. and Mrs. Roy Ryan of Evansville and five brothers and three sisters.

The family suggests that expressions of sympathy be in the form of contributions t the Chol-Chol Foundations, 4926 Loughboro Rd. NW. which assists Mauncchi Indians in southern Chile, or to the Immacelate Conception Church at 8th and N Street N.W.