- M 37/Bf 108A
- Initial version designed in 1934 for use in Challenge 1934. Six were built with the Hirth HM 8U, one other initially had a 220 PS (217 hp, 162 kW)Argus As17B inline engine and later a 160 PS (158 hp, 118 kW) Siemens Sh14A radial.
- Bf 108B
- Revised version, built from late 1935. Prototype had a Siemens Sh14A radial, but production machines used the 240 PS (237 hp, 177 kW) Argus 10C or the 270 PS (266 hp, 199 kW) Argus 10E. Quadrant shaped rather than rectangular rear window, tailwheel replacing skid, revision of shape of empennnage and removal of tailplane upper bracing.
- Bf 108 B-0
- Bf 108 B-1
- Bf 108 B-2
- Bf 108C
- Bf 108 C-1 Proposed high-speed version, powered by a 400 PS (395 hp, 294 kW) Hirth HM 512 engine. Probably not built.
- Bf 108 D-1
- Me 208
- Improved and enlarged version with a retractable tricycle landing gear. Two prototypes were built by SNCAN (Nord) in France during the war.