The Macchi M.C.99 was a prototype 1930s Italian twin-engined torpedo-bomber flying boat designed and built by Macchi.

The M.C.99 was designed by Mario Castoldi as a military flying boat, resembling the earlier commercial M.C.94 and was a wooden twin-engined shoulder-wing cantilever monoplane.

[1] Constructed mainly of wood, it was a high-wing cantilever monoplane flying boat.

[1] With a crew of five, it had an enclosed cabin and had defensive gun positions in the bow, amidships and in the tail.

[1] The prototype and only M.C.99 was powered by two 890 kW (1,190 hp) Isotta Fraschini Asso XI R.2C.15 engines, strut-mounted above the wings.