The high biodiversity level in Costa Rica reflects a complex topography as well as species input from South and North America, including the Caribbean. However, terrestrial malacofauna is not very diverse when compared with other groups such as insects. A possible cause is the scarcity of soil rich in calcium carbonate. Endemism is 31% in terrestrial species and 8% in freshwater species. A total of 233 species and subspecies have been reported from the country (50 freshwater and 183 terrestrial). Dangerous influences for the continental mollusks include water pollution, deforestation and the destruction of calcium-rich habitats (they have no legal protection). I recommend the protection of calcium-rich soil still covered by forest, wetlands, sites with high abundance or biodiversity, and mountain forests (especially those over 1500 m of altitude). Taxonomic and ecologic studies are the priority for conservation biology of the Costa Rican mollusks.
Keywords: endemic mollusks, Costa Rica, habitat destruction, endangered species