Despite heavy losses, in the Winter War the Red Army's 20th Tank Brigade, equipped with T-28s, fulfilled its mission to break the defensive Mannerheim Line. As an infantry-support tank, designed to support infantry in breakthrough operations, the T-28 in general was successful for an early 1930s design.
Model 1934''' or '''T-28A''' — main production model with the same machinegun turrets, and similar main turret as the [[T-35 ]] heavy tank and Model 27/32 76.2mm gun.
Model 1938''' or '''T-28B''' — version with improved L-10 76.2 mm gun (from 16.5 calibres to 26 calibres), improved gun stabilization system and improved Model M-17L engine.
* '''T-28E''' or '''T-28C''' — 1940 addition of appliqué armour in response to poor performance in Finland. Total front armour was increased to 80 mm, weight to 32 t, and road speed dropped to 23 km/h
Model 1940''' — the final batch of about twelve tanks had the same conical turret as late-production T-35 tanks.
=== Experimental models ===
Several self-propelled guns, the IT-28 bridging tank, and an engineering vehicle with [[mine roller]]s were tested on the T-28 tank chassis, but none was accepted for production. The T-29 was a prototype medium tank, a modernized T-28 with [[Christie suspension]] — a later version of this vehicle was considered for the competition of prototypes which led to the [[T-34]], but by then it was outdated (not to be confused with a Grotte tank project also called T-29). The T-28 also served as a testbed for the [[KV tank]] suspension.