The Avia B.534 was one of the few biplane fighters to see extensive action in World War II, it was also one of the few to be equipped with an inline engine giving it both a modern and an archaic look. It was the standard fighter of the Czechoslovakian air force during the second half of the 1930s until the German invasion when they ended up being operated by the Luftwaffe as fighters and, later, as trainers and glider tugs. It was later also adopted by the Slovak air force (under German control) where it reverted to its original role as a fighter and flown on the Eastern Front after Barbarossa (the few survivors then went on to fly against the Germans after the Slovak revolt of 1944). Other foreign operators included Greece, Yugoslavia, and Bulgaria which received a number of these aircraft after the occupation and used them against USAAF raids over Ploesti.

The prototype B.534 first flew in August 1933 and was developed from the earlier B.34 of which slightly over a dozen were built. Variants included the B.534-I with an open cockpit and wheel spats deleted, the B.534-II with guns on the forward fuselage, the B.534-III with wheel spats reinstated, and finally the B.534-IV which was the major production version and featured an enclosed cockpit. A minor variation resulted in the Bk.534 with one gun firing through the propeller hub and the B.632 testbed with redesigned wings and refined aerodynamic design.