The genus Leptopilina Förster is revised on a world basis. The identity of 31 nominal species, including type species of four other genera, is discussed and 15 lectotypes are designated. Valid species of Leptopilina are L. longipes (Hartig) [type species], L. clavipes (Hartig) n. comb., L. heterotoma (Thomson) n. comb., L. fimbriata (Kieffer) n. comb., L. rufipes (Cameron) n. comb., L. atraticeps (Kieffer) n. comb., L. mahensis (Kieffer) n. comb., L. boulardi (Barbotin et al.) n. comb., and L. cupulifera (Kieffer) n. comb. Leptopilina heterotoma is the valid name for the well-known Drosophila parasitoid currently referred to as Pseudeucoila bochei (Weld). Leptopilina is not synonymous with Ganaspis Förster. Tryhliographa Förster is a senior synonym of Episoclu Förster n. syn. and of Pseudeucoila Ashmead (synonymy confirmed). Leptopilina is described and compared with related genera (Cothonaspis, Rhoptromeris, Odonteucoila). L. victoriae n. sp. is described from the Seychelles. The five Leptopilina occurring in Europe are redescribed on modern material and a key is given to them.