The diversity of two subfamilies of cuckoo wasps in northeastern Brazil is reviewed. Four new species are described and illustrated: Amisega boyi Lucena, sp. nov., A. sertaneja Lucena, sp. nov., and Duckeia dudui Lucena, sp. nov. (Amiseginae), and Cleptidea nordestina Lucena, sp. nov. (Cleptinae). These new species of Amisega and Duckeia represent the first records of both genera in the core zone of the Caatinga dry region, and they seem to be endemic to this portion of the region. The other two Amisega species previously recorded in northeastern Brazil are restricted to ecotone habitats between Caatinga and Atlantic forest. Cleptidea nordestina Lucena, sp. nov. (Cleptinae) is the most septentrional record for the fasciata species group in South America. With the present contribution, the total recorded diversity of Amiseginae and Cleptinae in northeastern Brazil is represented by the following species: A. boyi Lucena, sp. nov., A. flavipes Kimsey, 1987, A. sertaneja Lucena, sp. nov., A. similis Kimsey, 1987, and D. dudui Lucena, sp. nov. (Amiseginae), and C. nordestina Lucena, sp. nov. (Cleptinae).