We conducted a long-term inventory of the herpetofauna of Wildsumaco Wildlife Sanctuary in the eastern part of the Napo Province in Ecuador. This private preserve is about 500 ha in size and is located on the southern slopes of Volcán Sumaco. The preserve contains primary forest, secondary forest, and pasture habitats. Based mostly on nocturnal transect sampling we documented 39 species of amphibians including one species of salamander, two species of caecilians, and 36 species of frogs. Rain frogs (Pristimantis Jiminez de la Espada, 1871) were diverse with 14 species documented. A diverse species assemblage of 45 reptile species was also documented on the preserve. Six amphibian species found were listed by the IUCN Red List. At least three species exhibited substantial geographic range extensions and seven species showed elevational range extensions. We discovered several undescribed species including one salamander, three frogs, one lizard, and one snake.