Kathleen Marie Kilcline, 25, a former student at Langley High School and a senior at the Indiana University School of Medicine, was killed Thursday in a traffic accident near Angola, Ind.

Indiana State Police said Miss Kilcline and her fiance, Dr. John Hemingway of Indianapolis, were fatally injured when their car was struck by a truck.

Miss Kilcline, the daughter of Rear Adm. Thomas J. and Dornell Kilcline of Washington, was scheduled to graduate from the medical school in February. An ensign in the Naval Reserve, she was to have been commissioned a lieutenant in the Naval Medical Corps upon graduation.

She was born in Fort Ord, Calif. She came to McLean with her family in 1969 and attended Langley High School there until tranferring to St. Mary's Academy in Leonardtown, Md., where she graduated in 1973. She was a magna cum laude graduate of St. Mary's College in Notre Dame, Ind.

In addition to her parents, she is survived by a brother, Navy Lt. Thomas J. Jr., of Miramar, Calif.; a sister, Mary Novak of Jacksonville, Fla., and her grandmother, Mary E. Thompson, of Pensacola, Fla. Another brother, Navy Lt. J. G. Patrick Kilcline, was killed in a plane crash in 1978.

The family suggests that expressions of sympathy be in the form of contributions in her name to St. Mary's College in South Bend.