Dr. Russell J. Fields, 85, a Washington dermatologist for nearly 50 years before retiring in 1979, died of arteriosclerosis Nov. 3 at his home in Washington.

Dr. Fields was a past president of the Medical Arts Society of Washington, the Washington Dermatological Society, the Social Hygiene Society of Washington and the Washington Rehablitation Bureau.

An authority on venereal diseases, he was the author of numerous technical works and had served as a consultant to the D.C. Health Department. He also had been a clinical professor at George Washington University.

Dr. Fields was a native of Dalton, Mass. He moved here about 1920 to attend Georgetown University, where he earned both undergraduate and medical degrees. He served internships at D.C. General Hospital and Mercy Hospital in Springfield, Mass. He practiced general medicine in Plymouth, Mass., and received training in dermatology at Bellevue Hospital in New York City, before returning to Washington about 1930.

In addition to his private practice, he served on the staff at Providence Hospital for more than 30 years. He had served as chief of dermatology at Providence Hospital, D.C. General Hospital and the old Doctors and Garfield hospitals in Washington.

Among his other professional affiliations, he was a life member of the American Academy of Dermatology. He also was a member of the Cosmos Club and had once organized an orchestra for physicians. He played the piano.

His wife, the former Christine Deegan, died in 1980. Dr. Fields leaves no immediate survivors.