Abstract Background The taxonomic position of enigmatic pygmy dormouse Typhlomys (Rodentia: Platacanthomyidae) from Vietnam is reconsidered based on both morphology and sequence data. Results The analysis of mitochondrial and nuclear genes has shown that the pygmy dormouse from Lao Cai Province of northern Vietnam belongs to a distinct phylogenetic lineage of Typhlomys . The DNA analysis has demonstrated a strong genetic difference (0.245 to 0.252 for the cytochrome oxidase gene (COI), 0.079 to 0.082 for interphotoreceptor retinoid-binding protein gene (IRBP), and 0.028 for the growth hormone receptor gene (GHR) between this lineage and the sample from South China. Multivariate analysis of cranial and dental data, as well as of some external characters, has also separated the Vietnamese population from the pygmy dormouse from Fujian in southern China, the type locality of Typhlomys cinereus (Bull Soc Philomath Paris 12:8–10, 1877). Conclusions Both genetic and morphological data confirm that there is a second species, Typhlomys chapensis (Field Mus Nat Hist Zool Ser 18:193–339, 1932), in the heretofore monotypic genus Typhlomys .