John G. Frank, 82, professor emeritus of languages at American University, died Wednesday of myocardial infarction at the Washington home of his son, Dr. Randolph Adams Frank.

Dr. Frank joined the faculty of American University in 1948 as a professor of modern languages. At his retirement in 1968, he was named professor emeritus.

He was fluent in more than a dozen languages, including Russian. He had developed an interest in that country and its people while he was a prisoner of war there during World War l. He subsequently became a scholar of Russian literate. He also wrote German-language textbooks for college students, including a premedical text in wide use for many years.

Dr. Frank was born in Blankenburg, Bavaria. During World War l he served in the German army as a lieutenant on both the Eastern and Western fronts. He and his company were captured by the Russians and imprisoned in Russia until their release in 1917, at the onset of the Russian Revolution. Dr. Frank then led his troops on foot back to Bavaria from Rumania.

In 1923, while a university student in Munich, he met his wife Irene Adams, an American music student. They were married the following year, after he joined her at her home on Princeton, N.J.

He later enrolled at the University of Michigan, where he earned a doctorate in modern languages in 1930, and was elected to Phi Beta Kappa.

He taught German at Vanderbilt University in Nashville until joining American University.

After his retirement in 1968, Dr. Frank and his wife traveled extensively. Mrs. Frank died in 1973.

In addition to his son, he is survived by a sister, Victoria Scherer, of Blankenburg, West Germany, and three grandchildren.