Small mammals were surveyed in the lowland forest of the Gonja Forest Reserve of north-eastern Tanzania. In 565 trap-nights 10 rodents (three species) were captured. In 12.5 net hours 27 bats (11 species) were netted. Comparisons of similar surveys in nearby montane forests indicate a lower density and diversity of rodents and shrews in Gonja than in higher elevation habitats. Information is presented on external measurements, weight and reproductive condition of the specimens collected.