Developed from the M-18, the first M20 prototype flew on February 26, 1928, and crashed on its initial flight killing the pilot Hans Hackmak. The second aircraft flew on August 3, 1928.

There were 3 models: a,b, and b2.

13 aircraft went to DLH and one to DVS. A number of crashes led Lufthansa to refuse to accept any more M20s, which resulted in the Messerschmitt company, Bayerische Flugzeugwerke (BFW) going bankrupt on 1 June 1931.

Eight survivors went to the Luftwaffe as trainers, the last one crashing in 1943. One was sold to Varig in Brazil in 1937 and flew on to 1948.

M 20b
Engine: 1 x BMW-VI, 500kW
Max take-off weight: 4800 kg / 10582 lb
Wingspan: 25.5 m / 83 ft 8 in
Length: 15.9 m / 52 ft 2 in
Height: 4.2 m / 13 ft 9 in
Wing area: 65.0 sq.m / 699.65 sq ft
Max. speed: 220 km/h / 137 mph
Cruise speed: 180 km/h / 112 mph
Ceiling: 5000 m / 16400 ft
Range w/max.fuel: 1000 km / 621 miles
Crew: 2
Passengers: 8-10

The M18a was a successful 4 seat, single-engined airliner built for Nordbayerische Verkehrsflug AG and others 1925. Developed into M-20.