Polyunsaturated fatty acids omega-3 and omega-6 play an important role in human organism, providing normal functioning of nervous cells, infl uence neurotransmission, make building elements of cellular membranes and take part in the productions of eicasonoids such as prostaglandins, thromboxanes, leukotrienes and lipoxins. Both epidemiological data and the results of neurobiological studies point to an association between a defi ciency of fatty acids of omega-3 type, and depression. The outcome of a number of clinical studies may indicate that the addition of fatty acids to antidepressant treatment augments the effi cacy of the therapy of depression, occurring in the course of the both unipolar and bipolar affective disorders. There are also studies demonstrating therapeutic effect of fatty acids of omega-3 type used as monotherapy, in postpartum depression. The promising results obtained so far on the favorable effects of fatty acids in the treatment of depression need confi rmation in further studies.