The Heinkel HD 37 was a fighter aircraft, designed in Germany in the late 1920s, but produced in the USSR for Soviet Air Force service.

It had been designed for the clandestine air force that the Reichswehr was training at Lipetsk, but had been rejected by German officials, who purchased the Fokker D.XIII instead.

The Soviet Air Force was experiencing a crisis with the obsolescence of its main fighter, the Polikarpov I-5, with no replacement apparently forthcoming from domestic manufacturers.

While the basic design was apparently sound, Soviet test pilots reported many deficiencies in handling, and Heinkel was presented with a long list of complex changes to be made.

Many of the improvements that had been adopted in the creation of the HD 43 were eventually implemented in the I-7 as well, along with other modifications, and by the time the first examples flew in summer 1931, flight test results were positive.