Objective The Israeli National Psychiatric Hospitalization Registry is a nationwide list of all psychiatric hospitalizations in the country and has been widely used as a source of data for psychiatric research. This study assessed the sensitivity of the diagnosis of psychotic disorders ( International Statistical Classification of Diseases, 10th Revision [ ICD-10] F20.0-F29.9) and schizophrenia ( ICD-10 F20.0-F20.9) in the Registry. Method Registry discharge diagnoses of psychotic disorders ( ICD-10 F20.0-F29.9) and schizophrenia ( ICD-10 F20.0-F20.9) were compared with research diagnoses derived from best-estimate procedures based on Research Diagnostic Criteria (RDC) using structured clinical research interviews, hospital records, and family information. Results Out of 169 patients meeting RDC for psychotic disorder, 150 also had a diagnosis of psychotic disorders in the Registry, yielding a sensitivity of 0.89. Re-running this analysis for the narrow definition of schizophrenia identified 94 patients who were diagnosed with schizophrenia using RDC; 82 of those patients also had a diagnosis of schizophrenia in the Registry, yielding a sensitivity of 0.87. Conclusion In 87% to 89% of cases with psychotic disorders or with schizophrenia, Registry diagnoses agreed with RDC diagnoses, a rate of agreement comparable with those of other, similar registries. Because a large number of analyses derived from this and similar national registries will be published in the coming years, this constitutes relevant information.