With more than 300 described endemic species, the land snail fauna of French Polynesia is of high conservation value. However, many species are extinct or threatened: 159 species from the region are recorded as extinct by the IUCN. A biodiversity inventory was done in the Austral islands (French Polynesia), during which molluscs were sampled 70 years after the 1934 Bishop Museumâs Mangarevan Expedition. Altogether, 248 taxa, 80% of which endemic, are now known from the Austral islands, most of them being small to minute species. More than two thirds of the endemic species are now extinct, and alien mollusc species have appeared and are much more widespread and abundant than indigenous ones. The main reason for endemic species extinctions seems to be habitat degradation through agriculture and urbanisation, fires, introduced goats and cattle and invasive plants. Euglandina rosea is present only in Tubuai, where it has an impact on Partula hyalina, but has not yet reached the other Austral islands. Introduced carnivorous Streptaxidae have been found in all islands, but their impact is not known, neither is the impact of other introduced invertebrates. The extreme fragmentation of native habitat, together with the very small range of many endemic species poses a further threat to their survival. Species new to science and already extinct have been discovered. All these facts makes the IUCN figure a very optimistic one, which will greatly increase when updated. Relict habitats for molluscs and other taxa have been discovered and proposed for conservation.