Dr. Mario Mollari, 84, retired chairman of the department of bacteriology, immunology and tropical medicine at Georgetown University medical school, died Friday at his home in Northwest Washington.

During his long career in the field of health, Dr. Mollari served in the Austrian Army as a medical officer in World War I, and worked with Albert Schweitzer at Dr. Schweitzer's hospital in Lambarene in Gabon.

Dr. Mollari, who held an M.D. degree from the Leopold University in Graz, Austria and a doctorate in tropical medicine from the University of Paris, came to the United States in 1924 and joined the Georgetown faculty the same year.

In 1958 it was estimated that 90 per cent of the school's alumni had studied under him. He retired about 15 years ago.

While a member of the Georgetwon faculty Dr. Mollari went to South and Central America in the summers of 1925, '27, '29 and '31, to study malaria, yellow fever and plague in Colombia and Ecuador and blinding filaria in Guatemala and Mexico.

Dr. Mollari was born in April 2, 1892 at Pieve di Livinalongo, which was then part of the Austro-Hungarian empire and later became part of Italy.

In 1911 he completed the Obergymnasium in Ljubljana, now part of Yugoslavia. He entered the medical school at Innsbruck, Austria, and was one year away from his degree when World War I broke out in August, 1914 and he found himself in the Austrian Army.

Dr. Mollari served throughout the war as a medical officer in charge of a medical unit attached to an artillery group, detailed to the Russian, Serbian and Romanian fronts.

When he completed his medical studies after the war he entered the service of the government of Belgium and was sent to the Congo. After illness cut short his stay there he came to the United States.

He became a department chairman and full professor at Georgetown in 1931. Georgetown gave him an honorary degree of doctor of science in 1956 and made him professor emeritus in 1967.

He was a member of many learned societies and was a past president of the Society of American Bacteriologists.

In addition to his work in Latin America, he returned to Africa in the summers of 1956, 57 and 58 to pursue his interest in tropical medicine.

He held many honors including the Legion of Honor from France, and was named a Commander of the Order of Merit by Italy.

Survivors include a son, Oscar M., of the home, a daughter, Nina Pesare, of Providence, R.I., a brother, Oscar, of Baltimore, two grandchildren and a great-grandson.