Violence committed by acute psychiatric inpatients represents an important and challenging problem in clinical practice. Sociodemographic, clinical, and treatment information were collected for 1324 patients (677 men and 647 women) admitted to Italian public and private acute psychiatric inpatient facilities during an index period in 2004, and the sample divided into 3 groups: nonhostile patients (no episodes of violent behavior during hospitalization), hostile patients (verbal aggression or violent acts against objects), and violent patients (authors of physical assault). Ten percent (N = 129) of patients showed hostile behavior during hospitalization and 3% (N = 37) physically assaulted other patients or staff members. Variables associated with violent behavior were: male gender, <24 years of age, unmarried status, receiving a disability pension, having a secondary school degree, compulsory admission, hostile attitude at admission, and a diagnosis of schizophrenia, bipolar disorder, personality disorder, mental retardation, organic brain disorder or substance/alcohol abuse. Violent behavior during hospitalization was a predictive factor for higher Brief Psychiatric Rating Scale scores and for lower Personal and Social Performance scale scores at discharge. Despite the low percentage of violent and hostile behavior observed in Italian acute inpatient units, this study shed light on a need for the careful assessment of clinical and treatment variables, and greater effort aimed at improving specific prevention and treatment programs of violent behavior.