The research was conducted at the Clinic for Psychiatry of the Rijeka Clinical Hospital Center with the purpose of determining the impact of the new Law on the Protection of Persons with Mental Disorders (LPPMD) on the frequency of involuntary hospitalization. It has covered two investigated periods: The first investigated period is the period of application of the old LPPMD from 01.01.2012. until 31.12.2014. and the Second Investigated Period is the period of application of the New LPPMD from 01.01.2015. until 31.12.2017. In addition to comparing the frequency of involuntary hospitalizations, the study includes diagnostic criteria, socio-demographic data as well as ways of approach to the Clinic (Police, Emergency Medical Assistance, Family) and the means of separation and restrictions. For the purposes of research, data from the Protocol on Involuntary Hospitalization, the History of Disease and the Integrated Hospital Information System were used. Analysis of the obtained results showed that there is no statistically significant difference in the frequency of involuntary hospitalization according to the old and new LPPMD, although when observing the examined periods we can notice the tendency of increasing the frequency of involuntary hospitalization according to the new LPPMD. According to the results of the research, the majority of involuntary hospitalized patients are male, 46.6 (SD 13.9) years old, unmarried, with finished high school education, unemployed, diagnosed with F20-F29 - schizophrenia, schizophrenia-like disorder and insanely state and F10-F19 - Mental disorders and behavioral disorders caused by the use of psychoactive substances, forcibly hospitalized in police escort, and some of the means of separation and restriction were applied to them.