Studies on population dynamics and community structure for mammals from the semi-arid Caatinga biome are very scarce. I surveyed non-volant mammals in four sites in the Caatinga of Northeastern Brazil. Herein, 24 species belonging to eight orders are recorded. A total of 165 individuals of five species of small mammals were captured in a 4-year capture-recapture study. Capture success and relative richness were low and not correlated with precipitation and temperature. The present study contributes to the knowledge of species biology and ecology in sites geographically close to priority areas for conservation in this biome.