Dr. Sarah Bedichek Pipkin, 64, professor of biochemical genetics in the department of zoology at Howard University, died of cancer Sunday at Bethesda Naval Hospital.

She had worked mainly with graduate students, focusing on the chemical function of chromosomes. The research done by her and her students was considered helpful in investigating the causes of cancer.

Born near Deming. N.M., Dr. Pipkin received bachelor's, master's and doctoral degrees from the University of Texas, where she was elected to Phi Beta Kappa.

In 1938 and 1939, she was a Rockefeller Foundation fellow in mathematical genetics at University College in London. She then taught for three years at Northern Texas State College.

During World War II, while her husband, the late Dr. Alan C. Pipkin Sr., a specialist in tropical diseases, served overseas with the U.S. Navy, she toured this country, giving slide lectures on Great Britain and sending the proceeds to London to aid victims of the German bombing.

After the war, she and her family traveled to many foreign countries where she carred out research on drosophila, genus of flies.

Dr. Pipkin collected and described previously undiscovered species in such remote places as the ruined Roman temples at Baalbek in Lebanon. Japanese war wreckage in the Truk atoll in the Southwest Pacific, rain forests in Panama, and along the upper Amazon River in Colombia and Brazil.

She first came to Howard University in 1957, as a research associate under a National Institutes of Health grant, and remained there two years.

She then was a research associate for five years at the Gorgas Memorial Laboratory in Panama, and was at Johns Hopkins University from 1954 until returning to Howard to teach and continue research in 1966.

Dr. Pipkin was the author of numerous scientific papers and belonged to a number of scientific organizations.

She and her husband moved to Simpsonville, Md., in 1964, and she had lived there since then. Her husband, who was retired from the Navy Department, died in 1973.

She is survived by three sons, Alan, of Purcellville, Va., Roy, of Glendale, Calif., and George, of San Francisco, and a sister, Dr. Mary Carroll, of Austin, Tex.

The family suggests that expressions of sympathy may be in the form of contributions to the E. E. Just Memorial Fund in care of Howard University.