The Letov Š-31 was a fighter aircraft produced in Czechoslovakia in the early 1930s in a number of variants.

After testing at the Czechoslovak flight facility at Prague-Lethany, modifications were undertaken to improve the machine's performance.

It entered production the following year and began equipping Czech fighter units in June 1936.

The machines however did not remain in frontline fighter status with the Czechoslovak Air Force until the German occupation of Czechoslovakia in 1939.

Data from Tschechoslowakische Flugzeuge : von 1918 bis heute,[2] Jane's All the World's Aircraft 1934[3]General characteristics Performance Armament