The first worldwide revision of the wasp genus Ufens Girault, 1911 (Hymenoptera: Trichogrammatidae: Oligositinae) is presented. Ufens is known to parasitize primarily hemipteran eggs and is a cosmopolitan genus most common in temperate and semi-arid regions such as the southwestern United States and Australia. Forty-three species are recognized here. Included in the revision are five species formerly in the genus Ufensia, herein synonymized, and 32...