The Re. 2000 was developed with the vision of a light and highly maneuverable interceptor and fighter aircraft for Mussolini’s Italian Air Force, or the Regia Aeronautica. Just one look at the aircraft shows that it drew upon many design elements the American Seversky P-35. It also had fully retractable landing gear and its armament consisted of a pair of 12.7 mm nose-mounted machine guns. On 24 May 1939, the prototype took to the air, and soon, it proved itself to be not only a sound aircraft, but superior to the Macchi C 200 and the Bf 109E in several respects, including top speed and maneuverability. For mostly arcane political reasons within the Italian defense establishment, the Re 2000 was rejected. So, Regianne turned to export, and about 80% of the entire production run went to Hungary and Sweden, though the Regia Aeronautica operated a mere five Re. 2000s. The type was also the basis for several derivatives from the Reggiane Re. 2001 to the Re. 2007 fighters.
During the war, Sweden’s Re. 2000s, re-designated as the J 20, mostly patrolled their country’s airspace, maintaining their sovereignty from both from Axis and Allied aircraft into 1945. In Hungarian service, Re. 2000s were sent to the Eastern Front against the Soviet air force, and they began to accumulate kills in what was regarded as a satisfactory combat record into 1943. However, as losses mounted and more capable Russian fighters emerged, the remaining Hungarian Re. 2000s were recalled for home defense duties. In Italian service, the few Re. 2000s saw combat in the Mediterranean theater in escort and attack roles, and a single kill against a Bristol Blenheim was recorded. Latent issues involving maintenance, unpredictable engine reliability, and performance in the air took a combined toll, and by 1942, the remaining aircraft were withdrawn from active duty.