An epidemiological study on clonorchiasis sinensis was conducted in 62 counties and cities in Hubei Province during 1987-1991, and clonorchis sinensis was identified in 52 counties and cities. Human population studies showed there were patients with clonorchiasis sinensis in 29 of 31 counties and cities investigated, with infection rates of 0.1%-16.2%. There were five species in two families of freshwater spiral shells as first intermediate host of clonorchis sinensis, 31 species in seven families of freshwater fish (with five species of fish newly discovered) and one species of freshwater shrimp as second intermediate host, and six species as reservoir host. Studies revealed holding small fish in the mouth and eating undercooked roasted fish were two major modes of transmission for clonorchiasis sinensis in the province.