Aim, material and method: The aim of the study was to assess the occurrence of bipolar disorder in subjects (N= 246) receiving treatment due to recurrent depressive disorders. A structured questionnaire based on the diagnostic criteria of major depression and (hypo) mania according to DSM-IV, the criteria of bipolar spectrum disorder by Ghaemi et al. and the Mood Disorder Questionnaire by Hirschfeld, was used. In 19.5% of the subjects, bipolar I disorder was diagnosed, in 35% -bipolar II disorder, and in 12.6% -bipolar spectrum disorder. Such symptoms as excessive sociability, excessive interest in sex, risk and unusual behaviours or irrational money spending were diagnostically the most characteristic of bipolar disorder. Results: Brief episodes of (hypo) mania, including those induced by the use of medicines, as well as the early onset were related to the highest probability of the occurrence of bipolar disorders.