The Macchi M.40 was a prototype 1920s Italian catapult-launched reconnaissance floatplane designed and built by Macchi, it did not enter production.
The M.40 was an all-metal equal-span biplane powered by a Fiat A.20 piston engine. It had a large central float with a stabilising float under each wing. The crew sat in tandem open cockpits and the M.40 was armed with one fixed and one movable machine-gun. Two were built, given the serials MM.88 and MM.89, but following testing, the aircraft was not put into production.