Inventory and distribution of molluscs in the Alinyà valley: basic information for the conservation and management of the area.-Eighty points have been sampled in the Alinyà valley, Alt Urgell, Catalonia. In the samples collected 67 species of molluscs have been identified. Eurosiberian elements dominate, followed by Mediterranean ones. The number of Iberian or Pyrenean endemics detected in the area is 12. The majority of species show scattered and restricted distributions. Xerocrassa salvanae, an endemic of the Pyreneees and the Iberian Levant, is the most widespread species. It is concluded that as far as the molluscs are concerned conservation programmes should be centred on preserving those species that have the most restricted distributions and are associated with poorly represented habitats: Cochlodina laminata, Neohoratia globulus and Pisidium personatum. The contribution of the molluscs to monitoring the quality of the environment should be based on species sensitive to environmental changes. A useful parameter to monitor is the influence of the altitudinal gradient on the molluscan community.