In recent years many cryptic bat species have been unmasked by differences in their echolocation calls. The yellow house bat (Scotophilus dinganii) is 1 of 3 species of Scotophilus currently described in southern Africa and is distinguished from the other 2 species by its size and yellow venter. Here we use genetic, morphological, and echolocation call data to show the existence of a cryptic species. We found that S. dinganii consists of 2 forms, one that uses a peak echolocation frequency of 44 kHz and the other a peak frequency of 33 kHz. Both forms have yellow venters. The 44-kHz phonic type is up to 15% smaller than the 33-kHz phonic type and differed genetically by an average cytochrome-b (Cytb) sequence divergence of 3.3%. Furthermore, combined phylogenetic analyses of Cytb and control region sequences indicate that the 2 phonic types are reciprocally monophyletic, suggesting that they are sibling species.