ITHACA, N.Y. -- Stephen J. "Doc" Roberts, who as an undergraduate, led Cornell University's polo team to its first national championship and then, as a veterinarian, coached the university's polo team to eight national championships, died in Bath, N.Y., Jan. 21, 2005, of heart failure. He was 89.

Roberts coached the Cornell polo team between 1947 and 1972, and his teams participated in 14 national championships, winning eight in 25 years. (The winning years: 1955, '56, '59, '61, '62, '63 and '66.) He was the captain of the team when he was an undergraduate.

He developed innovations in intercollegiate polo that remain to this day. To balance the competition of the sport, Roberts introduced the concept of "split strings" at the intercollegiate level. Visiting teams no longer had to transport their own horses to distant matches. Instead, the home team provides mounts, and the horses are exchanged between chukkers.

As a Cornell professor and veterinarian, he authored over 150 scientific articles and a classic textbook in 1956, Veterinary Obstetrics and Genital Diseases , which was published in three editions -- the final one in 1986. He was among the early faculty members to advocate a research component in faculty appointments, now a common practice. And he championed more equine research at Cornell.

Roberts served on the Judicial Council of the American Veterinary Medical Association (AVMA), and he was a charter diplomate of the American College of Theriogenologists. He was an associate editor of the Veterinary News and provided years of service to the Cornell Veterinary Alumni Association. He received the prestigious national Borden Award from the AVMA for his research on cattle disease, the Distinguished Service Award from the New York State Veterinary Medical Society and the Salmon Award given only to Cornell's most august veterinary alumni.

Born in Indianapolis on Aug. 5, 1915, Roberts grew up in Hamburg, N.Y., where his father, James Roberts, Cornell D.V.M. 1912, practiced veterinary medicine. Stephen Roberts earned his doctor of veterinary medicine degree in 1938. While a student at Cornell, he enrolled in the ROTC field artillery unit and captained the polo team to its first national championship in 1937.

In 1938 he married Betty Jane Harris (Cornell '38), and they moved to Manhattan, Kan., where he taught veterinary medicine and earned his master of science degree. In 1942 he joined the faculty at Cornell. He was named a full professor in the Department of Large Animal Medicine, Obstetrics and Surgery in 1946 and served as chairman of the department twice: 1965-66 and 1969-72. Roberts retired from Cornell in 1972 to go into private veterinary practice in Vermont.

Roberts is survived by his wife, Ruth Shipman Roberts of Bath, N.Y.; daughter Gail Roberts of Asheville, N.C.; and son Stephen J. (Laura) Roberts Jr. of Skyland, N.C.; two step-daughters, Barbara Shipman of Pine City, N.Y., and Betty Joy (Paul) Marsh of Syracuse, N.Y.; brother Charles Roberts of Columbia, Mo.; sister Betsy Roberts of Washington state; three grandsons and three great-grandchildren. His first wife, Betty Jane and his brother James, predeceased him.

A memorial service will be held at Cornell at a future date. In lieu of flowers, memorial contributions can be made to either the Cornell College of Veterinary Medicine, Office of Alumni Affairs and Development, P.O. Box 728, Ithaca, N.Y. 14853, in his memory, or to the Doc Roberts Fund for Polo, Attention: John Webster, Cornell University Athletics, Teagle Hall, Campus Road, Ithaca, N.Y. 14853.