The small mammal fauna of Roraima State, Brazil, is little known. Sixteen species were recorded at the Ilha de Maraca. Habitat associations do not differ from those reported elsewhere. Trapping success was very low, especially for arboreal species; reasons are offered for this. Numerical abundance and breeding periodicity track seasonal rainfall patterns. Abundance, species numbers and community composition are in broad agreement with observed biogeographical patterns for Amazonia.