Dr. Margaret H. Sloan, 66, a researcher and administrator at the National Cancer Institute who specialized in the field of occupational cancer, died Dec. 10 at her home in Rockville. She had cancer.

In the course of her career at the NCI, which began in 1961, Dr. Sloan had wide experience in scientific exchanges with the Soviet Union. She began as a special assistant for international programs. In 1962, she represented the institute at the 8th International Cancer Congress in Moscow and helped negotiate cancer section of the U.S.-Soviet cultural exchange and scientific agreement. From 1975 until her death, she coordinated the U.S.-Soviet exchange on cancer control and cancer centers.

As a researcher and administrator, Dr. Sloan worked on assuring quality in health services systems, occupational and environmental cancer, radiation as a cause of cancer, and diagnostic and therapeutic radiology. Last year, she was named chief of the occupational cancer branch at the institute.

Dr. Sloan was born in Portland, Ore. She graduated from Swarthmore College and earned her medical degree at Washington University in St. Louis. She moved to the Washington area in 1944.

In 1950, she joined the National Blood Program at the National Academy of Sciences as assistant director of advisory services. She later became director. In 1958, she was one of six women physicians who took part in an exchange visit with Soviet women doctors.

Dr. Sloan was a member of the American Association for the Advancement of Science, the New York Academy of Sciences, the American Society of Clinical Oncology and the board of the American Cancer Society. She received the Director's Award from the National Institutes of Health in 1979.

Her husband, Dr. Ruell A. Sloan, a former curator of the Armed Forces Medical Museum, died in 1951.

Survivors include two sons, Harry Sloan of Rockville, and Ruell Sloan of Jeffersonville, Vt.; two daughters, Margaret Watkins of Dickerson, Md., and Susan Minear of Plattsburg, N.Y., and three grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the American Cancer Society, 344 University Blvd., Silver Spring, Md., for the Margaret H. Sloan Memorial Fund for Cancer Research.