The Mollusca Collection of the Oswaldo Cruz Institute (CMIOC) started in 1948 by Wladimir Lobato Paraense and Newton Deslandes, by the Special Service of Public Health, in Belo Horizonte, Minas Gerais, and it is held by the Laboratory of Malacology of the Institute since 1976. Nowadays, the collection comprises more than 7,000 lots of shells and animals preserved from all the Americas – since Canada to Tierra del Fuego - as well as several countries from other continents. The collection includes lymnic molluscs of the families Planorbidae, Pomatiopsidae, Hydrobiidae, Lymnaeidae, Physidae, Ancylidae, Ampullariidae and Thiaridae (Gastropods); Corbiculidae and Sphariidae (Bivalvia), most of then preserved in Railliet-Henry solution, but also in 70% alcohol. With approximately 150 000 specimens of molluscs, the CMIOC is source for more than 150 publications of the Laboratory and supports various activities such as identification, loan of specimens, and qualification of human resources in medical malacology and systematics. The collection is arranged in catalog number sequence and it is fully databased. Since 2005, the CMIOC is faithful depository of genetic heritage within the Brazilian Ministry of Environment.