The Tam Dao National Park protects one of the best-preserved natural forest remnants of Northern Vietnam, which belongs to the diversity centres of the subfamilies Phaedusinae and Garnieriinae (Clausiliidae). Based on published records and our new data, we provide an overview the clausiliids of this important protected area and discuss their zoogeographical significance. The recent survey led to the rediscovery of Synprosphyma gastrum, an endemic species that has not been found since the end of the 19th Century. Three other species of the national park, Notoptychia polydona, Oospira semipolita and Phaedusa dichroa, are rare, sporadically occurring clausiliids that are confined to remnants of natural forests in Northern Vietnam.