New epidemiological data indicate a significant prevalence of bipolar affective disorder. The results of a Polish multicentre study conducted in 2002 show that among patients who have experienced a depressive episode, up to 60% may be depressive syndromes in the course of various forms of bipolar affective disorder. Recently, new pharmacological agents have been introduced that can be used in the treatment of bipolar affective disorder. These include antiepileptic drugs and second-generation neuroleptic drugs.