A collection of frogs was made in Madagascar between November 1970 and May 1973. Observations in the field and investigations in the laboratory yielded a variety of new taxonomic characters, such as the morphology of eggs and larvae, the reproductive behaviour, the habitat and habits of both the terrestrial and aquatic stages, the mating call and the colouration in life. Karyotype studies and researches on the nuclear DNA amount of these frogs were published previously. Because of various contradictions between the results of this study and the current classification, both these new and the more convential morphological characters were used for a re-evaluation of the systematics of the Mantellinae Laurent, 1946. As a result, this subfamily can be considered once more a natural, probably mono-phyletic group of ranid-type frogs, primarily separated from the others by a different mating behaviour. Of the genera Mantidactylus Boulenger, 1895, Mantella Boulenger, 1882, and Aglyptodactylus Boulenger, 1919, 35 species, collected by the author and representing about 70% of the known species, are treated. The genus Aglyptodactylus is excluded from the Mantellinae. The genus Gephyromantis Methuen, 1919, is synonymized with Mantidactylus. The broadened genus Mantidactylus is divided into 10 species groups: guttulatus group, ulcerosus group, lugubris group, albofrenatus group, aglavei group, asper group, boulengeri group, wittei group, depressiceps group, pulcher group. These groups reflect the adaptive radiation within this genus. Two new species are described: viz. Mantidactylus flavobrunneus and M. punctatus. Lectotypes are designated for Rhacophorus depressiceps Boulenger, 1882, Rhacophorus pulcher, Boulenger, 1882, Rhacophorus liber Peracca, 1893, and Gephyromantis methueni Angel, 1929. The following new combinations, new synonyms and bonae species are proposed: Mantidactylus grandidieri Mocquard, 1895, bona species (syn. Mantidactylus piger (Mocquard, 1900)); Mantidactylus opiparis (Peracca, 1893), bona species (syn. Mantidactylus melanopleura (Mocquard, 1901) and Mantidactylus frenatus Boettger, 1913); Mantidactylus aglavei (Methuen & Hewitt, 1913), comb. nov. (from Rhacophorus); Mantidactylus boulengeri (Methuen, 1919), comb. nov. (from Gephyromantis); Mantidactylus eiselti (Guibé, 1975), comb. nov. (from Gephyromantis); (Guibé, 1975), comb. nov. (from Mantidactylus blommersae Gephyromantis); Mantidactylus domerguei (Guibé, 1974) comb. nov. (from Gephyromantis); Mantidactylus peraccae (Boulenger, 1896), comb. nov. (from Rhacophorus); Mantidactylus tornieri (Ahl, 1928), bona species; Mantidactylus pulcher (Boulenger, 1882) comb. nov. (from Gephyromantis); Mantidactylus liber (Peracca, 1893), comb. nov. (from Gephyromantis), bona species (syn. Gephyromantis albogularis Guibé, 1947 and Gephyromantis variabilis Millot & Guibé, 1951); Mantidactylus bicalcaratus (Boettger, 1913), comb. nov. (from Gephyromantis) (syn. Gephyromantis methueni Angel, 1929).