The main causes of early mortality in patients with schizophrenia are comorbid somatic diseases (primarily cardiovascular diseases, diabetes, and obesity) and suicide, which reduces life expectancy on average by ten years compared to the general population. The COMT gene encodes catechol-O-methyltransfer- ase. This enzyme is responsible for O-methylation, one of the main pathways for catecholamine inactivation. The MAOA gene encodes monoaminoxidаse type A, an enzyme that carries out oxidative deamination of dopamine, norepinephrine, and serotonin. We hypothesized that polymorphic variants of the COMT and MAOA genes are associated with suicidal behavior in patients with schizophrenia. Accordingly, the aim of our study was to investigate the associations between the presence or absence of a history of suicidal behavior in patients with schizophrenia and polymorphic variants of the COMT and MAOA genes. A total of 150 patients of Slavic ethnicity with schizophrenia were examined. The presence or absence of a history of suicidal tendencies was determined based on medical records and a clinical interview. The control group consisted of 134 apparently healthy military personnel. Seven polymorphic variants in the COMT gene and two polymorphic variants in the MAOA gene were selected for pilot genotyping. Polymorphic variants of the COMT and MAOA genes were initially determined using PCR. An association was found between the COMT rs4680 and rs4633 polymorphic variants and a history of suicide attempts in patients with schizophrenia. The results of our study demonstrate the possible contribution of the catechol-O-methyltransferase gene to the mechanisms of suicidal behavior in patients with schizophrenia.