Twelve bat species of the genus Murina (Vespertilionidae: Murininae) were recorded in Vietnam: Murina annamitica, M. beelzebub, M. chrysochaetes, M. feae, M. cyclotis, M. eleryi, M. fionae, M. harpioloides, M. huttoni, M. leucogaster, M. tiensa, and M. walstoni. The skull measurements of 11 out of the 12 species were osteometrically examined using principal component analyses (PCA) based on 33 craniodental measurements from 150 specimens. Our analyses indicated that according to the overall skull size, the studied species could be divided as follows: large species (M. tiensa and M. fionae), medium-sized species (M. huttoni, M. cyclotis, M. annamitica, M. beelzebub, M. walstoni, and M. feae), and small species (M. eleryi, M. chrysochaetes, and M. harpioloides). The three size clusters did not overlap with each other in terms of total length of the skull (STOTL), mandible length (ML) and log-transformed raw data PC1 scores. Within a cluster, several species pairs overlapped in overall skull size despite of differences in the shapes. The PCA results suggested that Murina species of Vietnam were differentiated with a combination of the skull size and shape. Sexual dimorphism was confirmed in M. cyclotis and M. annamitica, with the females larger than the males. Particularly, M. cyclotis showed extensive sexual dimorphism with no overlaps in the measurements, whereas M. annamitica showed less measurable differences between the sexes. It was also evidenced that the extent of sex-biased size dimorphism differs among species in the genus Murina.