Three new species of Begonia section Erminea A.DC. from north-east Madagascar are described and illustrated. They share a tuberous habit, four tepaled male flowers and six tepaled female flowers, which are typical of that section. Begonia ambanizanensis Scherber. & Duruiss., sp. nov. differs from the other species in that section by the symmetric, sub-orbicular, succulent leaf blades. Begonia ambodiforahensis Scherber. & Duruiss., sp. nov. is compared to B. antongilensis Humbert and B. erminea L'Hér. but it differs from both by the combination of an acaulescent habit and the numerous lanceolate leaves with red margins and spiculiform red hairs on the blade. Begonia harimalalae Scherber. & Duruiss., sp. nov. is also compared to B. erminea from which it differs by the thicker, larger leaves, which are glabrous, with the margins shallowly and sparsely serrate vs densely biserrate.