Advances in the molecular genetics research into the etiology of affective disorders are outlined. Two approaches are used in the research: the candidate gene method and the whole genome screening. The paper presents findings of studies using the former approach, where the candidate gene (theoretically associated with the etiology of a given disorder) is selected. The studies refer mostly to biochemical concepts of affective disorders etiology. Reported findings of these studies indicate that in bipolar affective disorder a significant role is played by genes coding tyrosine hydroxylase, catechol-0-methyltransferase, monoamine oxidase type A and B, gamma-aminobutyric acid receptors and adenosine triphosphatase, while in unipolar affective disorder the D4 dopamine receptor coding gene may be of importance.