The relationship between mental illness and violent behaviour, particularly in schizophrenia, is an important issue both for health care professionals and the general public. Estimates of the prevalence of violence among schizophrenic patients vary according to patient selection, patient setting, and the definition of violence employed. This study investigated the occurrence and characteristics of violence and its clinical correlates among 698 schizophrenic patients who had been treated in an Irish general psychiatric hospital. Violent behaviour occurred in 16% of patients. The vast majority of acts were of a minor nature and serious physical assault was noted in only 1% of cases. Our findings are discussed with reference to the available literature.