(Uploaded by Plazi for the Bat Literature Project) Mammals from the Caatinga of Assú, State of Rio Grande do Norte, northeastern Brazil. Our knowledge of the mammalian fauna of the Caatinga has increased considerably in the past two decades. However, many areas remain under surveyed, as is the case of the state of Rio Grande do Norte. In this paper we present a list of the mammals documented for the municipality of Assú, in the ecoregion designated the Northern Sertaneja Depression (Depressão Sertaneja Setentrional) of the Caatinga Biome. The research was conducted as part of the environmental impact assessment for the Photovoltaic Center Assú V and associated transmission lines, together with a preliminary survey conducted in the Açu National Forest. Nine survey trips and two faunal rescue and relocation actions were conducted between March and December of 2017. We used the following survey approaches: direct observation, detection of signs, collection of road kills, camera traps, pit traps, live traps, mist nets, and bat roost searches. We documented 22 resident native species (such as Callithrix jacchus, Pteronotus gymnonotus and Wiedomys cerradensis), including two threatened species (Leopardus emiliae and Puma yagouaroundi), belonging to 16 families and seven orders. We also observed the presence of three domestic species and three exotic invasives. This richness is similar to that observed in other previous surveys of short and medium duration in the Caatinga. However, the low number of bat species detected and the absence of several species of regularly hunted medium and large body-size mammals likely reflect local environmental disturbance, influenced by the alteration of the natural vegetation, increased hunting pressure, and the presence of domestic species.