A new species of the genus Hypleurochilus (Teleostei: Blenniidae) from Trindade Island and Martin Vaz Archipelago, Brazil.  A new species of the genus Hypleurochilus, endemic to Trindade Island and Martin Vaz Archipelago, off Brazil, is described. Hypleurochilus brasil sp. n. differs from its congeners in color pattern and anal-ray counts. A recent study shows a close relationship between H. brasil sp. n. and H. fissicornis. This new species is recorded from 3 to 15 m depth, solitary or in small groups (up to 10 individuals), always in small holes or associated with sea-urchins and sponges on the rocky reefs. Hypleurochilus brasil sp. n. is the eleventh recognized species of Hypleurochilus and the third species of this genus reported from the Brazilian Province.