KENNEBUNKPORT, MAINE -- John Walker, 81, a retired surgeon and investment banker who was an uncle of President Bush, died Aug. 16 at a hospital in Biddeford, Maine. He had an aneurysm.

Dr. Walker, who lived on a farm in Easton, Md., had summered in Kennebunkport most of his life. He was the brother of the president's 89-year-old mother, Dorothy Walker Bush.

He was a graduate of Yale University and Columbia University medical school. He switched careers from medicine to finance after he was stricken with polio in 1950. He became a managing partner in G.H. Walker and Co. in New York and a limited partner of Alex Brown Inc.

He also became president of Memorial Sloan-Kettering Hospital in New York City, according to the White House press office.

It was on Dr. Walker's recommendation that the Bushes brought their 3-year-old daughter Robin to Sloan-Kettering for treatment in 1953 after a doctor in Midland, Tex., told them she was dying of leukemia.

Bush, in his 1987 autobiography, "Looking Forward," wrote:

"After we came home from the doctor's office, I called my uncle, Dr. John Walker, in New York City. He was president of Memorial Hospital there and a former cancer specialist. When I told him the news about Robin, he urged us to bring her to New York, where early research into leukemia was being conducted at Memorial Hospital by the Sloan-Kettering Foundation. Maybe nothing could be done, he told us, but we would never forgive ourselves if we didn't try. Even if the odds were a hundred million to one, said John, 'You've got to give life a chance.' "

The little girl spent the last six months of her life at the cancer center, where Barbara Bush stayed at her bedside while George Bush shuttled between Midland and New York City. She died in November 1953, a few weeks before her fourth birthday.

Dr. Walker was an Army major in World War II, serving in the European theater. The son of the donor of the Walker Cup, he was an avid golfer until stricken by polio.

Survivors include his wife, Louise Mead Walker of Easton; three sons, Judge John M. Walker of New York City, George Mead Walker of Severna Park, Md., Randolph Talbott Walker of Easton; and a daughter, Elsie Walker Kilborne of Narberth, Pa.; two sisters; two brothers; and six grandchildren.