The involuntary hospital treatment is presented as one of the most current problem in psychiatry at all, but not enough explored problem in Serbia. In spite of the fact that it has come to important contemporary of psychiatric service, however the number of involuntary hospitalized patients is still on high level - in some countries above 80% in relations to totally number of hospitalized patients. A primary aim of this study was to adjust comparative analysis of determined reasons for voluntary or involuntary hospital treatment of mental ill persons. This study involved 1274 patients which were hospitalized in Special Psychiatric Hospital nearby Nish, during the period of one calendar year. There were 435 voluntary hospitalized patients (34,1 %) and 839 involuntary hospitalized patients (65,9 %). The most often determined reasons for involuntary hospitalizations were: delusions, hallucinations and aggressive behavior.