Scott Ruigh Mazzur, 46, a senior research scientist and head of the viral epidemiology section of the American Red Cross Blood Services Laboratory in Bethesda since 1973, died of cancer Friday at Georgetown University Hospital.

Dr. Mazzur, a microbiologist and immunologist, was a specialist on hepatitis B (Australia antigen). Her research on the epidemiology of hepatitis in the Solomon Islands for about seven years laid the foundation for her work at the laboratory. There she applied results of her studies of a tropical population with a relatively high incidence of the disease to American carriers of the virus.

In 1966, Dr. Mazzur earned a doctorate in microbiology from the University of Pennsylvania for her studies on interferon, an antiviral drug now being tested as an anticancer agent. She then became director of a viral diagnostic laboratory for the New Jersey State Department of Health.

She joined the Institute of Cancer Research in Philadelphia in 1969, where, as a research assocaate, she worked with Dr. Baruch S. Blumberg, a geneticist whose work on hepatitis B earned him the 1976 Nobel Prize for medicine. He had discovered the Australia antigen in 1963 and later linked it to hepatitis.

Dr. Mazzur was responsible for establishing a viral diagnostic laboratory in the Dominican Republic and initiated testing of blood donors for hepatitis in the Solomon Islands medical department.

She was born in Princeton, N.J., and earned a bachelor's degree from Rutgers University in 1957.

She was a member of the American Association for the Advancement of Science and the American Association of Microbiologists.

Her husband, Robert, died in 1977.

Her survivors include two children, Anna and Frank, and a sister, Pamela Ruigh, all of the home in Potomac, and her parents, Dr. William L. and Mary Ruigh, of Washington.

The family suggests that expressions of sympathy be in the form of contributions to the Washington Cathedral Building Fund.