We report on seven new localities for Mantella bernhardi, a Malagasy poison frog that was previously known only from a single site. This species has been considered threatened with extinction because of ongoing habitat destruction and collection for the pet trade (up to c. 3,000 specimens per year). The new localities considerably extend the known range of this species, which has now been documented from c. 21.00° to 24.15°S and 47.00° to 48.00°E, and over 60–629 m altitude. Two of the sites are within protected areas (Ranomafana National Park and Manombo Special Reserve). An overlap analysis of the potential distribution area of the species, based on the extent of remaining primary vegetation, indicates that the habitat of M. bernhardi in south-eastern Madagascar is fragmented and populations may be relatively small and isolated. We support the IUCN Red List category of Endangered for this species and highlight the need for detailed studies of its populations.