Through the continuous and intensive investigation of the marine molluscan fauna of Greece and the collection of live and dead specimens during the last two years, 23 gastropod species were identified up to the species level (four philinids up to the genus level), all belonging to 14 families. Their biodiversity was compared with the current checklists of marine gastropod molluscs for the Hellenic seas based on previous surveys. In this collection of mainly minute species, 15 are new for the Greek fauna, one of which is alien (Murchisonella columna) and one, Melanochlamys wildpretii, is first record for the Mediterranean Sea. The main identification characteristics and ecological information such as habitat, distribution and origin are given and discussed.