Aim. The aim of this paper was to evaluate the impact of augmenting administered antidepressant treatment of patients suffering from a severe episode of treatment-resistant recurrent depression or bipolar affective disorder with omega-3 fatty acids and comparing the obtained results with those achieved in the groups of patients potentiated with lithium or lamotrigine. Methods. The research subjects were 21 patients diagnosed with a severe episode of treatment-resistant recurring depression in the course of recurrent depression disorders - or bipolar affective disorders. Patient eligibility included failure to respond to at least two 4-week antidepressant treatments (venlafaxine at a dose of up to 300 mg/day or paroxetine at up to 60 mg/day). The regular antidepressant treatment regimen was augmented by the eye-q preparation with a course of 24 capsules per day (2.2 g of EPA, 700 mg of DHA, 240 mg of GLA, 40 mg of vitamin E, primrose oil). The patients received the preparation for at least 4 weeks. The comparison groups consisted of the patients suffering from the current episode of severe treatment-resistant depression, treated by potentiating antidepressant treatment with lithium and lamotrigine. Results. The initial intensity of depression symptoms on the HDRS scale was 30 +/- 6, following a 4-week potentiation HDRS score was 11 +/- 10. Taking into account a significantly higher initial intensity of depression, clinical improvement upon administering fatty acids was proportional to the one achieved by potentiating therapeutic effects with lithium and lamotrigine. Effectiveness resulting from the use of omega-3 fatty acids in a positive correlated with baseline severity of depression and in a manner adverse to the duration of the current episode. The use of high doses of omega-3 significantly decreased the levels of triglycerides, increased the HDL and LDL, did not result in adverse changes in liver enzyme values. Conclusions. Augmenting a standardised antidepressant treatment with omega-3 fatty acids resulted in a marked improvement in depression symptoms measured on the Hamilton scale in the majority of patients with treatment-resistant depression. Clinical improvement upon administering fatty acids was proportional to the one achieved by potentiating therapeutic effects with lithium and lamotrigine. The use of high doses of fatty acids did not cause significant side effects.