 There are good reasons to suppose that Vietnam, with a surface of 332,000 km2, a large variety of habitats, and many different limestone 'islands' that differ from each other in faunal composition, will have a rich diversity of terrestrial molluscs.Numerous non-marine mollusc species, including more than 850 species of land gastropods, have been described from the country but many others still await discovery and description.Freshwater gastropods in Vietnam include