The Mikoyan-Gurevich MiG-3 was a Soviet fighter aircraft used during World War II. It was a development of the MiG-1 by the OKO (opytno-konstrooktorskiy otdel — Experimental Design Department) of Zavod (Factory) No. 1 to remedy problems that had been found during the MiG-1's development and operations. It replaced the MiG-1 on the production line at Factory No. 1 on 20 December 1940 and was built in large numbers during 1941 before Factory No. 1 was converted to build the Ilyushin Il-2.