We report the results of a terrestrial small mammal survey at one National Park in the northeastern Brazil, in the state of Pernambuco. The Catimbau National Park is located within the Caatinga domain with the characteristic thorn scrub vegetation. Our sampling encompasses several different vegetation/habitat types within the park area. All specimens collected were prepared as vouchers to be deposited in the Museu de Zoologia da Universidade de São Paulo. Karyotypes were obtained for all representative purported species collected. We report here the results of this first survey – two species of marsupials and seven of rodents - and added new occurrence localities for several small mammal species of this region, provide karyotypic information and register an undescribed species of arboreal rat of the genus Rhipidomys. This survey illustrates the need for extensive and planned sampling of the Caatinga domain.