The LF-57 is a sub machine gun of Italian origin. It was developed in the mid 1950's by Luigi Franchi. The name is derived from the initials of its developer and the year of introduction. Although the LF-57 functioned well it saw little sales due to competition from contemporary designs such as the M12, MP5 and Uzi.

The LF-57 is a blowback operated weapon that fires from an open bolt position. It bears much resemblance to the prototypes that led to the development of the Beretta M12. The LF-57 is made of stampings and pressings and features a steel wire shoulder stock. A unique design feature is the recessed bolt above the barrel, which makes the weapon shorter but requires a higher receiver.

The LF-57 fires the 9x19mm NATO round from a 20 or 40 round magazine. The LF-57 fires fully automatic only and has a cyclic rate of fire of 500 rpm. Since it fires from an open bolt position it is not very accurate, but this is offset by its capability of prolonged automatic fire. The maximum effective range is about 150 to 200 meters.

The LF-57 was only adopted in limited quantities by the Italian military. Most LF-57 were sold to African nations and very few ended up in other continents. Nowadays most LF-57 probably are scrapped and only limited quantities remain in service.