The collection of molluscs (Mollusca) contains over 15000 specimens and includes 4 classes: chitons (Polyplacophora), snails (Gastropoda), mussels (Bivalvia) and cephalopods (Cephalopoda). The first materials were collected around 1900. Molluscs were collected by S. Iurinitsh, I. Buresch, N. Radev, A. Markovich, A. Valkanov, etc. The collections of P. Drensky and A. Angelov present the rich freshwater malacofauna of Bulgaria. The collection of B. Russev includes over 1200 sites from all freshwater water basins in the country. The molluscs of the Aegean Sea are abundantly represented in the collection of A. Petrov. Indo-Pacific molluscs were donated by D. Yolova. A large number of alien species have been collected by P. Beron. The collection of S. Damjanov includes the Bulgarian terrestrial forms. Many underground forms were collected by I. Buresch and P. Beron. Recently the new materials are connected with the invasive molluscs.