Summarizes the results of the author's investigation of the endemic genus Physodeutera Lacordaire, 1843. Relevant type material and more than 2200 other specimens deposited both in institutional and private collections were examined. All species-group taxa are treated, one new subgenus proposed and an additional six new species are described. 64 species and 6 subspecies are arranged into 8 subgenera. The distribution and behaviour of adults are supplemented with the author's own experience obtained in the course of his four excursions to Madagascar.