Seven hundred and eighty-five individuals from an area endemic for Schistosoma japonicum had parasitological and physical examinations done. A morbidity questionnaire was also administered to each participant. Among those with S. japonicum infection, there was a significant increase in diarrhea, blood in the stool and weakness during the previous two weeks. The severity of the disease appears to be related to the history of schistosomiasis japonicum and these results give further justification for treatment of the infected individuals and those severe morbidity groups in community based chemotherapy programs designed to reduce morbidity in endemic areas.