Noticing the public health importance of mental disorders, the CIPH established the Croatian Psychosis Registry back in 1961. It started operation by taking a census of all persons with diagnose of mental disorder found in psychiatric hospitals and wards on 31 December.

The Registry is a special health-statistical instrument for long-term patient monitoring, also having the characteristics of a population registry It monitors data on persons residing in Croatia who suffer from schizophrenia or schizoaffective disorders (codes F20.* and F25.*, ICD-10) and  are treated in inpatient health care institutions.

In addition to the method of registration (regular hospital, day hospital, census/found on Dec. 31 in hospital), data on the health institution, data on the hospitalized person and data on hospitalization are also recorded. Data are routinely analysed at person and case level within individual subgroups of the so-called contingents: new patients/first admitted (hospital incidence), admitted, discharged, total hospitalized, and hospitalized on the day of the census.