The materials of Instituto Oswaldo Cruz Pathology Department Collection (PDC) relate to the activities of this Department as 1984, and include biological materials and documents related to human materials and experiment animals. Based on more than 16 thousand cases, the collection has a great number of pieces preserved in formaldehyde solution, paraffin blocks (65 thousand), slides with stained histological sections (240 thousand), forms used to sent materials to the Histotechnology Sector of the Department, and analogical and digital images of pieces in formaldehyde solution and histological preparations (more than 500 thousand images). Such materials hold a history of more than 25 years of scientific research, which provides important information on diseases, such as schistosomiasis and angiostrongyliasis, as well as human physiology, as in hematopoiesis.