SU-37, source: Aviarmor.net with permission of the operator, edited

The idea of building a self-propelled anti-tank gun based on the light amphibious T-37 tank originated in 1935. Army command looked favourably on the concept and authorised development work to begin. A prototype of the new vehicle was completed within the same year and testing could commence.

The original tank chassis had to be lengthened for the new purpose. A fifth road wheel was added on each side of the running gear, supplementing the existing four. The self-propelled gun's weight exceeded that of the original tank, and lengthening the chassis was intended to address this — the longer hull helped distribute the weight more evenly and improved the vehicle's handling characteristics. The positions of the drive sprocket and idler wheel were also swapped: whereas the T-37 had the drive sprocket at the front and the idler at the rear, the SU-37 reversed this arrangement.

The turret was removed from the hull and replaced by a fixed superstructure at the front of the vehicle. In the centre of its front wall was a 37 mm Model 1931 anti-tank gun, with a ball mount for a 7.62 mm DT machine gun to its left. Two crew members sat inside the superstructure — the driver and the commander, who also doubled as gunner and loader. The prototype was completed and put through its trials still in 1935. Despite satisfactory test results, the vehicle was ultimately not accepted for series production, and only the single prototype was ever built.