Marinduque is an island province of volcanic origin and is found in the southern portion of the Luzon Group of Islands. The island has an uneven topography but has experienced drastic deforestation in recent times. Records on the terrestrial snail species diversity in the Philippines in general and Marinduque in particular are sparse in the zoological literature. Previous literature noted only 13 species in Marinduque, which could be a gross underestimation of the terrestrial malacofaunal diversity of the island because the area was not systematically surveyed. This study aimed to assess the malacofaunal biodiversity of Marinduque and prepare a comprehensive list of snail taxa via opportunistic sampling. Sampling was conducted in 12 pre-determined areas of the island, with emphasis on minimally disturbed areas. This study reported ten (10) new records of stylommatophoran species and six (6) new records of terrestrial prosobranch species in Marinduque, which brings a total of 24 terrestrial snail species known to date (or 26 if two previously recorded species that were not encountered in this study are included).