The Letov S-328 was a robust one-engine biplane aircraft produced in Czechoslovakia during the 1930s. It was originally designed for Finland, but its export was never realized. The Letov factory continued to produce them and 445 aircraft were delivered in a period between 1934 and 1939. It was used as reconnaissance plane and a light bomber in pre-war Czechoslovak Air Force. During WWII it served in German, Slovak and Bulgarian air forces. It was one of the last biplane aircrafts used in combat role.