Caicaras are inhabitants of the Atlantic Forest coast in SE Brazil. We studied the uses of plants by five Caicara communities and compared medicinal plant citations by informants in coastal and island communities.. We use diversity indices to evaluate the use of plants and to compare communities. There is a high diversity of plants used in the Atlantic Forest coasts: we found 276 species used for food, medicine and construction. Caicaras rely on folk medicine, and medicinal plants were especially cited in interviews. Following predictions of island biogeography theory, we Sound a lower diversity of medicinal plants cited in islands compared to continental communities.534387395