Objectives: The aim of the study was to examine whether the postpsychotic decline in IQ during schizophrenia coincides with psychopathological deterioration or it is a state-independent premorbid impairment. Methods: The IQ score of 32 schizophrenic patients and 25 normal comparison subjects were evaluated three times during an average of 4,5 years, after short (mean 2,3 years) and long (mean 4,6) follow-up periods. The results were examined and related to changes of negative and positive symptoms of the illness. Results: The schizophrenic group had lower IQ score at baseline than the normal comparison subjects but showed comparable stability over time. The total IQ score slightly increased in both groups in follow-up period. No significant correlations were found between IQ score changes and, improvement or worsening of the clinical symptoms. Conclusions: The IQ score of patients with schizophrenia appears to remain stable regardless of psychopathological decline, and even could be improved by learning and rehearsal.