Production of the first 100 MiG-1's commenced immediately following the conclusion of the flight testing program in September 1940. The testing program had revealed that the MiG-1 was not without flaws. Its longitudinal stability, control responses, and handling were all regarded as inadequate, so a redesign was commenced even as the first production MiG-1's were being built.
The MiG-3 was the result of the program to improve the MiG-1. The MiG-3 was primarily built around a steel tube frame with duralumin skin. The new ship was visually similar to the MiG-1, but the engine was moved forward 4" to change the center of gravity, the dihedral of the outer wing was increased 1 degree to improve stability, the airframe was strengthened, the height of the aft fuselage was reduced for better pilot visibility, the radiator fairing was moved forward and the supercharger intakes enlarged. To increase operational flexibility, a 55 gallon fuselage fuel tank was added along with four wing hardpoints. These allowed the MiG-3 to carry 440 pounds of bombs or 6-3.2 inch RS82 rockets. Pilot survivability was increased by the addition of 9mm seat armor and all fuel tanks were surrounded by inert gas to reduce the chance of fire or explosion due to battle damage.
The MiG-3 was ordered into production in December 1940. First deliveries of the new fighter to front line fighter squadrons occurred in April 1941. The MiG-3 remained in series production until the last week of December 1941, when it was discontinued due to the unfortunate unavailability of the AM-35A engine. Total MiG-3 production amounted to some 3120 aircraft, and 50 more were built from available parts during the first half of 1942. The MiG-3 remained in service almost to the end of the war, wrecked aircraft were often cannibalized to keep others flying.