Artturi Ilmari Virtanen (January 15, 1895 - November 11, 1973) was a Finnish Nobel laureate in chemistry.

Virtanen was born in Helsinki, Finland. He studied the Classical Lyceum at Viipuri, Finland. After he finished school, he studied chemistry, biology, and physics. In 1939 he became Professor of Biochemistry at the Finland Institute of Technology at Helsinki and at the University of Helsinki in 1939. His research included partially synthetic cattle feeds, nitrogen-fixing bacteria in the root nodules and improved methods of butter preservation.

In 1945 Virtanen became Nobel Prize Laureate in Chemistry, for his research in agricultural and nutrition chemistry, especially for his fodder preservation method (AIV Fodder). The method – which he had published 1943 - improved the storage of green fodder that is important during long winters. Process includes adding dilute hydrochloric or sulfuric acid to newly stored grain. Increased acidity stops harmful fermentation and has no adverse effect on the nutritive value of the fodder or animals that eat it.