The Avia B 534 was used by Bulgaria, Czechoslovakia, Germany, Greece, Slovakia, and Yugoslavia.
In 1937 the Avia B.534 competed in the International Aeronautical Meet at Zurich. The Czechoslovakian team won 2nd, 3rd, and 4th place. The winner was the Bf 109.
The 4th Air Regiment was first equipped with the Avia B.534 in 1935.
The Avia B 534 was one of the few biplanes that saw active service in World War II.
Greek Air Force
The Greek Air Force received six B 534-IIIs before the start of World War II.
Yugoslavian Air Force
The Yugoslavian Air Force received fourteen B 534-IIIs before World War II started.
When the Germans occupied Czechoslovakia in March 1939 the Luftwaffe took over around 450 B 534s. The were used as fighters, trainers, and glider tugs.
Slovak Air Force
When the Slovak Air Force was created 70 B 534s were transferred to their control.
Three squadrons were equipped with the B 534 and sent to the Russian front in July 1941.
In the Slovak revolt of 1944 three surviving B 534s were used against the Germans.
Bulgarian Air Force
The Bulgarian Air Force received 78 B 534-IVs. Some were used in the defense of Ploesti.