Abstract The ecology of Asian rainforest mongooses is very poorly known. The short-tailed mongoose (Herpestes brachyurus) is found in rainforests throughout Southeast Asia and very little is documented about its natural history and ecology. Here, we present results from the first radio telemetry study of this species. We captured seven short-tailed mongooses in Krau Wildlife Reserve, Peninsular Malaysia and radio-tracked five adults (three males and two females). Our observations confirmed that this is a solitary, territorial species. The mean home range size of males (233 ha, 95% MCP) was larger than females (132 ha). Females had exclusive home ranges (mean overlap was 3.7%), and male home ranges overlapped more than one female's range. Short-tailed mongooses showed a diurnal activity pattern: mean activity between 06:00 and 17:59 h was 84.7%. The mean minimum distance covered during a 24-h period by males (842 m) was significantly greater than females (468 m). Short-tailed mongooses were mainly found in lowland forest. Deforestation and pollution of watercourses could have serious impacts on this species across its range.