The northern most portion of Atlantic Forest is currently considered as the most vulnerable and threatened in this ecoregion, while also harboring the ecoregion’s least studied biota. Herein we present results of a herpetofaunistic survey in Refúgio de Vida Silvestre (Wildlife Refuge) Matas de Água Azul (RVSMAA), in the mountain range Serra do Mascarenhas, northeastern state of Pernambuco, Brazil, one of the largest forest remnants in the northern Atlantic Forest. The sampling was carried out in four expeditions using methods of visual searching and pitfall traps. A total of 43 species of amphibians and 40 species of reptiles were registered, including anurans, caecilians, lizards, snakes and chelonians. The richness recorded represented 56% of amphibians and 20% of reptiles registered in the Atlantic Forest north of the São Francisco River. The RVSMAA holds a high diversity of amphibians and reptiles, representing one of the highest levels of richness in the northern Atlantic Forest. The record of seven species included in some of the threatened species lists reinforces the importance of the area for the conservation of the Atlantic Forest herpetofauna and adds relevant information to our knowledge of northern Atlantic Forest biodiversity and aids in its assessment of conservation.