This paper concerns the genus Boophis Tschudi, 1938 ( = Malagasy Rhacophorus Kuhl & Van Hasselt, 1822). Apart from a reconsidering of adult morphology, certain new taxonomic characters, such as the colouration in life, the morphology of the tadpole and some mating calls, are presented. Karyotypes and nuclear DNA amount were reported upon elsewhere. This study produces a sharper definition of the endemic genus, permitting its clear separation from the genus Mantidactylus Boulenger, 1895. Various sibling species are reported; as a result different synonymies are revised and new species presented. Four new species are described, viz. Boophis mandraka, B. viridis, B. reticulatus and B. hillenii. A lectotype is designated for Rhacophorus majori Boulenger, 1896. The following bonae species, new synonyms and new combinations are proposed: Boophis erythrodactylus (Guibe, 1953), comb. nov. (from Hyperolius); Boophis difficilis (Boettger, 1892), bona species; Boophis miniatus (Mocquard, 1902), bona species; Boophis goudoti Tschudi, 1938 (syn. Rhacophorus fasciolatus Ahl, 1929 and Rhacophorus kanbergi Ahl, 1929); Boophis untersteini (Ahl, 1928), bona species; Boophis pauliani (Guibe, 1953), comb. nov. (from Hyperolius) Boophis microtympanum (Boettger, 1881), comb. nov. (from Rhacophorus boettgeri Boulenger, 1882: substitute name for Hylambates microtympanum Boettger, 1881).