This aircraft was designed by Pavel Beneš and Miroslav Hajn, engineers at the Czech aviation company ČKD-Praga in 1931. It flew for the first time in June of that year. The biplane, standard configuration for that era, was an immediate success and orders were placed by the Czech Air Force that used them as elementary training aircraft at its flight schools throughout the 1930s. Pre-World War II production of the machine was 139 units. Following the German occupation of Czechoslovakia in 1939, the eastern area of that country was divided politically into the separate state of Slovakia. Under a puppet German government it became a German ally and its small air force was placed under Luftwaffe control. Ten of the Praga E-39s were given to the Slovakian Air Force which initially used them as trainers but during the German invasion of the Soviet Union, transferred several of them to the Soviet front where they were employed by the Slovaks as reconnaissance platforms in support of German ground forces. Other E-39s were used by the Luftwaffe in their flight training schools as elementary trainers and still others were given to the Hungarian Air Force for use in that same role.