The Aermacchi AM.3 was the result of a joint venture between Aermacchi and Aeritalia in response to an Italian Army requirement for an aircraft to replace the Cessna L-19, and was initially designated the MB-335.

Aermacchi was an Italian aircraft manufacturer. Formerly known as Aeronautica Macchi, the company was founded in 1912 by Giulio Macchi at Varese in north-western Lombardy as Nieuport-Macchi, to build Nieuport monoplanes under licence for the Italian military. With a factory located on the shores of Lake Varese, the firm originally manufactured a series of Nieuport designs, as well as seaplanes.