According to CBT theory, belief system has an important role in etiology of depression. Absolutistic, rigid and irrational beliefs might have influence on development and persistence of depressive psychopathology. The aim of our study was to examine characteristics of irrational beliefs in the cognitive scheme of patients with Major Depressive Disorder (MDD).

The sample consisted of sixty inpatients diagnosed as MDD by using the ICD-X criteria. The assessment of irrational beliefs was carried out by Beck's Personality Belief Questionnaire (PBQ).

Our findings have shown that irrational beliefs related to histrionic, schizoid and paranoid cognitive system were the most prevalent in patients with MDD. We also found significant and high correlation between opposite way of thinking - histrionic beliefs pattern correlated with avoidant and schizoid beliefs patterns. Also, dependent belief pattern was in a significant correlation with avoidant, schizoid and paranoid beliefs. In addition to rigidity, absolutistic and imperative cognitive schemes, we also found ambivalent cognitive tendencies. The existing ambivalence could be an important factor in the maintenance of depressive symptoms.

Our study has shown high prevalence of irrational beliefs in MDD patients. By recognizing the exact cognitive biases underlying depression, it might be possible to direct the therapeutic interventions more specifically and provide a highly personalized approach in the treatment of patients with MDD. We also believe that there is a need for a psychotherapeutic work on irrational beliefs during remission, which might prevent relapses.