Biochemical abnormalities are thought to be important factors causing bipolar disorder. Several lines of evidence suggest dopamine may play a role in its etiology, e.g. depressive syndrome is frequently encountered in subjects affected by Parkinson's disease, where dopamine depletion is observed. Thus the genes of the dopaminergic system are good candidates for studies on bipolar disorder. In the present study, we investigated polymorphisms of dopamine receptors, type D2, including the dopamine receptors D2, D3 and D4.Polish bipolar patients (n=339) and control subjects (n=366) were analyzed for three dopamine receptor gene polymorphisms: dopamine receptor D2 (DRD2) 141 ins/del, dopamine receptor D3 (DRD3) Ser9Gly, and dopamine receptor D4 (DRD4) 521 C/T.Allele and genotype frequencies did not differ significantly among patients and controls. We did not obtain any significant association between the studied polymorphisms and bipolar disorder.The results suggests that the studied gene variants of type D2 dopamine receptors are not promising candidate genes for bipolar affective illness. We did not consider the family history of the examined subjects, and also the control group was not psychiatrically screened, which may contribute to the lack of significant results.