Subjects in the study were 856 patients hospitalized in 31 mental hospitals on the grounds of criminal detention. It has been found that within the past three months prior to the study 31% of the subjects manifested verbal aggression, and 19% – physical aggression. These behaviors were usually directed against other patients, less often – against the staff. In the same period almost 7% of the patients left the hospital willfully, while 9% attempted to do so. Within one month preceding the study physical constraint was used towards 9.2% of the patients.