The genus Phaedis of Sumatra is revised. Thirteen known species are recognised from the island and adjacent islands, in which eleven known species are redescribed or noted with additional description; eighteen new species are described under the following names, and a key to the species of Sumatra is given: P. coeruleovirenssp. nov., P. convexussp. nov., P. eleganssp. nov., P. kanieisp. nov., P. kraatzisp. nov., P. merklisp. nov., P. nanussp. nov., P. notaticollissp. nov., P. notatipennissp. nov., P. obscuripennissp. nov., P. obtusidenssp. nov., P. pubigasterussp. nov., P. purpureostriatussp. nov., P. rubripessp. nov., P. schultheissisp. nov., P. signatussp. nov., P. kaszabisp. nov., and P. yokoiisp. nov. A new species group, Shibatai species group, is proposed.