The Magyar Királyi Honvéd Légierő, Royal Hungarian Air force, was the main operator of the Re.2000. Hungary bought 70 Reggiane Re.2000 Falco Is and then also acquired the licence-production rights for this model to produce a total of 200 aircraft, known as Héja (Falcon) II built between 1940 and 1942. According to other sources,170–203 aircraft were built. The II series was the same aircraft with a different engine and Hungarian machine guns. The Hungarians used the Re.2000 fighters to serve on the Eastern Front. The first aircraft received from Italy were sent to Debrecen to strengthen the fighter defences, as there was danger that the growing crisis over Transylvania could lead to a conflict with Romania. Conflict was avoided and the Reggianes were used in the war against Soviet Union.
Combat performance against the Soviet Air Force was quite satisfactory. The first Hungarian ace of the war, 2/Lt Imre Pŕnczél, claimed his first air victories while flying the Re.2000, three of them in one sortie, in 1942. Hungarian fighter pilots flew Fiat CR.32s before, and as the Re.2000's flight characteristics were markedly different (being much more prone to stall and spin), it was not popular with all pilots. The Re.2000 was subject to a high accident rate, due to reliability issues and handling difficulties. When the first squadron deployed to the Eastern front, all 24 Re.2000s had suffered accidents (minor and major) within a month after combat deployment. Landing and takeoff accidents were common on the rudimentary Russian airfields and due to the Re.2000 not having a rugged landing gear compared to that of the CR.32 that also flew in the same theatre, this type suffered a higher proportional accident rate. After a steel plate was added behind the cockpit to protect pilots, the shift in the aircraft's center of gravity led to more frequent accidents. In a much publicized accident, István Horthy (the son of the Hungarian regent Miklós Horthy), serving as a fighter pilot with the Hungarian Second Army died on 20 August 1942, flying his Reggiane. He was on his 25th operational sortie with his Re.2000 V-421 from 1/3 Fighter squadron. A pilot flying above Horthy asked him to increase height, he pulled up too rapidly, stalled and crashed to his death.
While Hungary wanted an additional 50-100 Re.2000s without engine and armament (that could be locally manufactured), although other countries expressed interest including Finland (100 each), Portugal (50), Spain, Switzerland and Yugoslavia (with license production), no Reggianes were exported to any of them. Hungary continued to produce licence-built Hejas: 98 were completed in 1943 and 72 in 1944 although the variant was regarded as no longer suitable for combat against the latest Soviet fighters. The Luftwaffe was reluctant to re-equip the MKHL as German aircraft production was designated for front line use while the danger of a Hungarian-Romanian conflict still existed. Moreover, Adolf Hitler held a bad opinion of Hungarian aviators. In autumn 1942, he had replied to a Hungarian request for fighters:
"They would not use the single-seaters against the enemy but just for pleasure flights!... What the Hungarians have achieved in the aviation field to date is more than paltry. If I am going to give some aircraft, then rather to the Croats, who have proved they have an offensive spirit. To date, we have experienced only fiascos with the Hungarians."
Consequently, in April 1944, the Hungarians still deployed four Héja IIs in 1./1 Fighter squadron and four Hejas II in 1/2, all of them based in Szolnok for Home defence duties, along with about 40 Bf 109s and Messerschmitt Me 210s. The last sortie, for the licence-built Reggiane Re.2000, occurred on 2 April 1944. That day, 180 bombers from the USAAF 15th Air Force, escorted by 170 fighters, bombed the Danube Aircraft Works and other targets in Budapest. The Hungarian fighter control centre in the Géllert hill, near Budapest, scrambled one wing of Hejas from 1/1 Fighter squadron, along with 12 Bf 109G-4/G-6S and a couple of Messerschmitt Me 210Cas-1s from the Experimental Air Force Institute (RK1). The Hungarians reported 11 aerial victories, of which six were confirmed, while USAAF pilots claimed 27 MKHL aircraft shot down; later records showed only two Honvéd pilots were killed.