Dr. Kenneth L. Thompson, 90, Iowa's oldest active general practitioner and Oakland's hometown doctor for more than 60 years, died early Tuesday at Clarkson Hospital in Omaha. Thompson, who would have been 91 February 5, had first entered the hospital three weeks ago after a heart attack, then returned last week after a short stay at home.

Born in West Point, Nebraska, Thompson opened a one man medical practice in Oakland in 1921 after graduation from the University of Nebraska Medical School in 1918. In the following 61 years he served three generations of Oaklandites, delivered over 2,500 babies and supervised Red Cross blood donor programs in Hancock, Carson, Treynor and Oakland. He was a past president of the Pottawattamie County Medical Society. His wife, Ida, died in 1957.

Thompson was still putting in 35 hours a week at his office when he celebrated his 90th birthday this year, at a reception attended by more than 200 people. Other honors accorded him included the 1978 designation of an Oakland street as "Dr. Thompson Avenue." Thompson was a member of the Oakland Masonic Lodge, the Scottish Rite Consistory, Tangier Shrine, Order of the Eastern Star and the Oakland United Church of Christ.

Surviving are a daughter, Peggy (Mrs. Ralph) Baker of Clinton; a brother Harry, who address was unavailable; sisters May Rasmus of West Point, Nebraska, Florence Bartels and Lottie Simonson both of Scribner, Nebraska, Louise Johnson of Bellevue, Nebraska, and Marjorie Peterson of Omaha; and three granddaughters.