Inspired by the design of the F-86 Sabre, the Fiat G-91 was the winning design in a 1953 NATO competition for a light fighter-bomber, beating various other aircraft designs including the Northrop F-5. However, for political and industrial reasons rather than any failing in the basic design, it was only adopted in any significant numbers by the Italian and West German air forces. The aircraft first flew in Italy on 9 Aug 56, was powered by a single licensed built version of the Bristol Siddeley Orpheus 803 jet engine and was armed with either four machine guns or two 30mm cannon and could just exceed Mach 1 at altitude. The Italian Air Force eventually acquired 174 versions of the aircraft all built by Aeritalia who also delivered 144 versions to Germany. A more advanced version was later built in Germany under licence by a consortium of Messerschmitt, Heinkel and Dornier who eventually delivered 294 aircraft. A later version, the G-91Y, was developed by Aeritalia and used two General Electric J-85 engines. Portugal also purchased the G-91, eventually operating a fleet of 74 aircraft. The G-91 was phased out of service in Portugal in 1993.
In 1957 it was decided to develop a fighter reconnaissance version of the basic design, designated the G-91R, which was flown for the first time in 1959. This aircraft was equipped with three Vinten 70mm cameras in the nose, one each facing either side and one facing forward. This version equipped both Italian, German and Portugese reconnaissance squadrons for many years. Version of the G-91 were produced throughout the 1960s, however, the type has now been withdrawn from service by all three countries.