A new species of bat in the Hipposideros bicolor group, found in a very restricted area in Central Laos, is described. The new bat is very similar in general body size and shape to H. rotalis, a species whose distribution includes the known range of the new species. However the new species differs noticeably in the size of the noseleaf, rostral chambers, skull structures related to sound emission or reception, frontal skull width, and echolocation frequency. Both species are superficially very similar to H. orbiculus and H. ridleyi, from the Malayan peninsula, Borneo, and Sumatra, which had been considered sibling species of H. rotalis, perhaps implying vicariant speciation involving the Isthmus of Kra. The new species resembles H. orbiculus in its smaller internarial septum, and the echolocation frequency is also similar, but skull traits clearly ally H. orbiculus with H. ridleyi, which is sympatric with it in peninsular Malaysia. Molecular systematic analyses of cytochrome b nucleotide sequences of a sample of species in the H. bicolor group support the sister status between the new species and H. rotalis. However, H. ridleyi does not join the latter two in a monophyletic group, apparently having evolved similar morphology and echolocation convergently from a different ancestor.