Dr. William P. Herbst, 85, professor emeritus of clinical urology at Georgetown University and a pioneer in the treatment of prostatic cancer, died Dec. 30 of a pulmonary embolism at his home in Castle Gregory, Ireland.

Dr. Herbst was chief of the departmen of urology at Georgetown from 1946 to 1950. His research, which involved bladder function and the chemistry of prostatic and renal cancer, led to the introduction of estrogens in the treatment of prostatic cancer.

He also instituted the endrogen treatment of breast cancer.

In 1936, Dr. Herbst organized the residency training program in urology at the old Gallinger Memorial Hospital, now D.C. General. In addition, he had been chief of urology at Doctors Hospital here.

He also served as a civilian consultant in urology to the National Naval Medical Center in Bethesda and to the Walter Reed Army Medical Center here and was a consultant to the National Institutes of Health Clinical Research Center.

In 1966, he was appointed to a four-year term on the National Advisory Arthritis and Metabolic Diseases Council as an adviser on grants and the awarding of programs.

A native of Washington, Dr. Herbst earned a medical degree from Georgetown University in 1915. He served his internship at Georgetown from 1915 to 1916 and was a resident physician at Columbia Hospital for Women here the following year.

Dr. Herbst served in the Navy medical corps from 1917 to 1919. He then became a fellow in surgery at the Mayo Foundation in Rochester, Minn., where he received training in urological diagnosis and surgery. He earned a master's degree in surgery from the University of Minnesota School of Medicine and served as an instructor in urology there from 1926 to 1933.

That same year Dr. Herbst returned to Washington, established a private practice and joined Georgetown University as a professor of clinical urology. At the time of his retirement in 1964, he was named professor emeritus.

Dr. Herbst helped in the establishment of the National Research Council's Committee of the Genitourinary System. He also was a founding member of Washington's Blue Shield Plan and a founder and past president of the Washington Urological Society.

In addition, he had served as president of the Medical Society of the District of Columbia, the American Cancer Society, the urology sections of the American Medical Association and the Southern Medical Society, the American Board of Urology, and the Washington Academy of Surgery.

He was a member of the urological committee of the National Research Council of the National Academy of Sciences and for many years was chairman of the research committee of the American Urological Association.

In 1959, Dr. Herbst received the St. George's medal and citation of the American Cancer Society for "outstanding service in cancer control."

He received the Guiteras medal "for outstanding contributions to urology" from the American Urological Association. In 1953, he received the Meritorious Pulbic Service Award from the D.C. government.

He was the author of many professional papers and a contributor to several urological texts.

Dr. Herbst and his wife, the former Catherine Arnold, moved to Castle Gregory, Ireland, five years ago.

In addition to his wife, of the home, he is survived by three children, Dr. William P. III, and Patricia Howell. both of Washington, and Robert V.C., also of Ireland.