Both "Phedina" martins have grey-brown upperparts and paler, heavily streaked underparts. Adult Mascarene martins of the nominate subspecies are long with wings averaging and weigh . The tail is slightly forked and the wings are blackish-brown. The Madagascan subspecies is overall paler and larger-billed than the nominate form. It has denser streaking on the breast, but only very fine lines on the lower abdomen and on the white undertail. It is distinctly smaller than the nominate subspecies, in length with an average weight of . The Brazza's martin is long with dark brown wings averaging . It has a brownish tint to the breast plumage and a square tail. Both species have dark brown eyes and a black bill and legs. Juvenile birds have more diffuse breast streaking, and white tips or buff edges to the feathers of the back and wings.