Schizophrenia is associated with cognitive deficits and information-processing anomalies. Several studies have shown impairments in frontal lobe functions such as discovering rules, adopting strategies and working memory. We have evaluated the performances of schizophrenic patients on three different tasks of information processing. The first was a simple reaction time task, the second consisted of discriminating the color of the stimuli, and the third required the use of a rule of permutation. The schizophrenic patients (n=17) showed a task-dependent increase in time for responses in comparison with the control group (n=17). This increase was particularly important in the last task, which requires the use of the rule. These results confirm and expand the previously described impairment of patients with schizophrenia in the ability to use rules. They are discussed in terms of deficit in executive functions probably due to frontal lobe malfunctioning.