Early trials of the T-37A revealed many deficiencies in its design, including limited range, sub-par buoyancy, and an unreliable transmission and running gear that could cause its tracks to fall off while on the move.

[1] While the production-model T-38 was only armed with a 7.62mm DT machine gun, the initial prototype vehicle also included a 20mm ShVAK cannon mounted on the driver's position.

The tank was incapable of supporting the weight of two infantrymen while floating, and overloads of 120-150 kilos would cause the commander's hatch to flood, sinking the vehicle.

[1] These flaws were to be fixed by the T-38's successor, the T-40, but only a small number were built before the outbreak of World War II, leaving the T-37A and T-38 to form the bulk of the Red Army's amphibious tanks.

In the confined terrain of Finland, the tank was a deathtrap; it also did not do well in the early stages of World War II, and large numbers were captured by the Germans during Operation Barbarossa.