This study deals with five species of the Barbirostris Complex of Anopheles subgenus Anopheles that are known to occur in Thailand. Three new species of the complex, Anopheles dissidens sp. nov., Anopheles saeungae sp. nov., and Anopheles wejchoochotei sp. nov., are characterized and compared with Anopheles barbirostris van der Wulp and Anopheles campestris Reid based on specimens of molecularly identified progeny broods. For practical purposes, the five species are essentially isomorphic and can only be unequivocally identified from diagnostic mitochondrial and ribosomal DNA sequences. Based on overall morphological similarity, An. campestris is considered to be a member of the Barbirostris Complex rather than a separate member of the Barbirostris Subgroup. The molecular data, mitotic karyotypes, bionomics, and distributions of the species are reviewed and discussed. It is concluded that integrated molecular epidemiological studies of the complex throughout the Oriental Region are needed to unambiguously elucidate the individual species and their relation to disease. © 2015 The Linnean Society of London