Twenty-four species representing 21 genera, 16 families and 7 orders of mammals were recorded in the Tripura state, northeast India, from an inventory done from 2006 to 2012. Ten of these species were found in wildlife sanctuaries as well as in primary forests. Four species were recorded exclusively from the wildlife sanctuaries and ten species were recorded only from primary forests. Order Primates was the most diverse group represented by 6 species from 4 genera in 3 families. Frequency sightings data showed that 11 species were rare, 2 species were occasional, one species was frequent, and another 10 species were common. Two species, Large-footed Mouse-eared Bat, Myotis sp., and Greater False Vampire Bat, Megaderma lyra, are new records from the study area. Overall, 23 of the 24 species recorded are listed in the IUCN Red List, 14 species are listed in CITES, and 14 species are protected under the Indian Wildlife Protection Act, 1972. Threats being faced by many of the recorded mammals from human encroachments are highlighted.