The Ro 57 made somewhat of a break with previous Meridionali practice, being a relatively advanced twin-engined single-seat interceptor with retractable landing gear. Designed in 1939 by Ing. Giovanni Galasso, the Ro 57 retained the mixed construction of the earlier machines with its wooden wings and duralumin-covered steel-tube fuselage, but the lines were considerably sleeker. The only anachronistic note was the braced tailplane, although the retractable tailwheel of the prototype was later discarded in favor of the fixed faired type, and armament was still only two 12.7-mm. Breda-SAFAT machine guns. The two 840 h.p. FIAT A.74 R.C.38 fourteen-cylinder radial engines were insufficient for the Ro 57's intended role of interceptor, maximum speed being only 311 m.p.h. at 16,400 ft. Manoeuvrability was only fair.
For these reasons, the small number of Ro 57's delivered to interceptor squadrons in 1942 were later withdrawn and adapted as fighter-bombers and dive bombers. In July, 1943, fifteen Ro 57's still equipped the 97° Gruppo Intercettori, of the 4a Squadra Aerea, based at Crotone; a few were pressed into the defense of Sicily. The dive bombing variant, designated Ro 57bis, was fitted with dive brakes, two 20-mm. cannon in addition to the 12.7-mm. guns, and a crutch for bombs up to 1100 lb. under the fuselage.
The interceptor had a cruising speed of 242 m.p.h., a range of 745 miles, and a service ceiling of 25,590 ft. Climb to 19,680 ft. took 9 min. 30 sec. Empty and loaded weights were 7694 lb. and 11,000 lb. Dimensions were: span 41 ft. 0 1/8 in., length 28 ft. 10 1/2 in., height 9 ft 6 1/8 in., and wing area 247.6 sq. ft.