Dr. Ralph G. Smith, 85, former acting director of the Bureau of Medicine at the Food and Drug Administration, died of cancer April 30 at Holy Cross Hospital.

Dr. Smith, a former head of the department of pharmacology at Tulane University Medical School and a professor of medicine at the University of Michigan Medical School, joined the FDA in Washington in 1950. He retired from the government in 1970.

His FDA service was concentrated on assuring the safety and efficacy of potentially hazardous new drugs, and it included positions as chief of the new drug branch and director of the division of new drugs within the FDA's Bureau of Medicine.

Dr. Smith was born in rural Ontario and received a bachelor's degree and a medical degree from the University of Toronto. He also received a doctorate in pharmacology from the University of Chicago.

In retirement, Dr. Smith had worked as a consultant on problems of drug addiction to the division of medical sciences of the National Research Council of the National Academy of Sciences. He also had been associate executive secretary of the National Research Council.

A naturalized U.S. citizen, Dr. Smith lived in Silver Spring.

Survivors include his wife of 52 years, Barbara Emily, of Silver Spring; four sons, Alan M., of Oakland, Roger M., of Silver Spring, Robert G., of Houston, and Eric J., of Arlington; a sister, Mary Dike of Kirkland, Ontario, and four grandchildren.