A study on the conservation status of the black rhinoceros (Diceros bicornis, L.) in the Ngorongoro Crater, Tanzania was undertaken in order to investigate recent allegations that this species is fast disappearing in the area. Comparison of census data on rhinos were made from 1958 to 1978 during which time there has been a notable steady decline in the mean population density mainly due to increased poaching pressure. Other factors that may have caused this fall are discussed. Urgent management measures to conserve the rhino population in the Ngorongoro Crater and the surrounding areas are recommended.