Results of the present comparative study of cognitive functioning of patients with schizoaffective disorder and schizophrenia are presented. Compared to patients with schizophrenia, SAD patients have a less pronounced memory and executive functioning deficits. Horizontal expansion that can be associated with increased impulsivity accompanying affective disorders was a distinctive feature of SAD patients' drawings. Obtained data contribute to the understanding of cognitive deficits in patients with endogenous psychoses and may contribute to the individualization and effectiveness of treatment and rehabilitation of these patients. Found differences in cognitive dysfunction testify in favor of the independence of diagnostic units of schizophrenia and SAD. Schizophrenia is accompanied by more severe cognitive deficit.