The Aermacchi MB-339 is an Italian military trainer and light attack aircraft. It was developed as a replacement for the earlier MB-326.

In September 1972, Aermacchi was awarded a contract to study a replacement for the Italian Air Force's MB-326s, comparing seven all-new designs (given the designation MB-338) powered by various engineswith an improved version of the MB-326, designated the MB-339. The MB-339 was considered to meet the Italian Air Forces requirements while being cheaper than the all-new designs which resulted in it being selected to replace both the MB-326 and the Fiat G.91T in Italian service.

The MB-339 is of conventional configuration and all-metal construction, and shares much of the 326's airframe. It has a low, un-swept wing with tip tanks and jet intakes in the roots, tricycle undercarriage, and accommodation for the student and instructor in tandem. The most significant revision was a redesign of the forward fuselage to raise the instructor's seat to allow visibility over and past the student pilot's head. The aircraft was fitted with a larger fin and powerplant for the initial versions was the same Rolls-Royce Viper 632-43, producing 4,000 lbf (17.79 kW), as fitted to the MB-326-K.