A prototype was built at Kirov Plant in 1950 and the tank was officially adopted on 6 August 1951 with the designation PT-76. Production started at the Stalingrad Tractor Factory (STZ). The tank was subsequently modified. In 1957, the D-56T gun was replaced with the D-56TM - with double-baffle muzzle brake and fume extractor - and the hull was raised by 13 cm, additionally the tank was equipped with new vision and communications devices. First series tanks were subsequently modified, receiving the D-56TM gun and new equipment. In 1959 an improved variant, the PT-76B, was adopted and remained in production until 1967 (main improvements were: D-56TS gun with stabilization and CBRN protection).