This study analyses the volume of illegal import of mollusc shells to Poland, the source countries and the departure regions, based on the Polish Customs Service reports for 1998–2015. The records comprised 444 shell seizures including giant clams (Tridacnidae spp.), queen conch (Strombus gigas), unionids (Unionidae spp.), South African abalone (Haliotis midae) and souvenirs made from mollusc shells. The seized and confiscated shells came from 73 countries from five regions of the world: East and Southeast Asia (mainly the Philippines, Malaysia and Indonesia), Wider Caribbean (mainly the Bahamas and the USA), the Red Sea, the Indian Ocean and the Western Pacific. Three groups of perpetrators were involved in illegal shell trade: tourists smuggling mainly shells of S. gigas, small-scale illegal traders importing similar numbers of queen conch and giant clam shells, and legal traders involved in illegal trade and/or criminal organisations smuggling mainly tridacnid shells as well as souvenirs made from mollusc shells.