Following extensive field work in Thailand (2006–2008), this paper reviews the taxonomic status of the three species of the Hipposideros bicolor group. Based on morphometric characters and acoustic data, the two phonic types, H. bicolor (131 kHz) and H. bicolor (142 kHz) are treated as distinct species. Hipposideros bicolor (131 kHz) is designated as H. bicolor; H. bicolor (142 kHz) is provisionally designated as H. atrox. The morphometric characters, acoustic data, and geographical distribution of H. pomona are also reviewed. The diagnostic characters of these frequently confused taxa are discussed, with a detailed study of the external, cranio-dental, and bacular morphology, and acoustic features. New data on the conservation status, distribution and ecology of these three species are included.