Aim. In the present work we tested the hypothesis of cognitive function disorder progression in schizophrenia. Methods. Current cognitive, clinical and functional status of 34 chronic schizophrenic patients (13 males, 21 females), with mean 31 year-long duration of illness, was assessed. For neuropsychological assessment we used WCST, TMT, Stroop Test and Verbal Fluency Test. Results were compared with performance of 30 age, sex and educational level matched healthy controls and 20 first-episode subjects investigated before starting the first pharmacological treatment. Results. Compared to first-episode drug-free patients, individuals with chronic schizophrenia performed worse on tests measuring psychomotor speed and shifting abilities (TMT A and B) and cognitive flexibility (more perseverative errors in the WCST). They also had more perseverations in letter and category Verbal Fluency Test. Discussion. These results are in accordance with data from studies indicating rapid cognitive dysfunction progression in later stages of schizophrenia. Obtained differences cannot be explained only in terms of age differences. In group of chronic schizophrenic patients, worse cognitive abilities were related to poor functional outcome in individuals with longer duration of illness. Conclusion. The results suggest that cognitive dysfunctions seem to have progressive character in the course of illness and are associated with present clinical and functional outcome.