A systematic revision of the Neotropical genus Nemobrenthus Sharp is carried out on the basis of morphological characters. Prior to this study, the group included eight nominal taxa. Only three species are actually considered valid-Nemobrenthus sublaevis Boheman from Atlantic Brazil, Nemobrenthus helmenreichii Redtenbacher from South-Central Brazil, and Nemobrenthus aeneipennis Sharp from Central America and the northern part of South America-as several new synonymies are proposed: Nemocephalus tonsus Kleine, n. syn. for Brenthus sublaevis Boheman; Nemocephalus gounellei Kleine, n. syn. for B. sublaevis; Brenthus suratus Boheman, n. syn. for B. sublaevis; Nemobrenthus expletus Kleine, n. syn. for Trachelizus helmenreichii Redtenbacher; Nemobrenthus bechynei Soares & Scivittaro, n. syn. for T. helmenreichii; Nemobrenthus pereirai Soares & Scivittaro, n. syn. for T. helmenreichii; Nemobrenthus melzeri Kleine, n. syn. for T. helmenreichii. Lectotypes are designated for B. sublaevis and N. tonsus. A key to the three recognized species of Nemobrenthus is provided.