Lithium was supplemented to antidepressant medication in 64 patients with major depression meeting the criteria for refractoriness to treatment. All the patients had previously undergone at least two treatments (pharmacological or ECT) with no satisfactory results. In the reported supplementary treatment with lithium carbonate the drug was introduced after at least 4 weeks of antidepressant medication. The dosage was targeted to produce serum lithium level between 0.6 and 0.8 mEq/l. After 4 weeks since lithium introduction symptoms of depression subsided in 35 (56%) of the treated patients. The remission was significantly more often noted in patients with depressive symptoms in the course of bipolar affective disorder (80%) than in those with unipolar affective disorder (48%): moreover, it was more frequent in patients with less pronounced depression (73%). In 24 cases a marked amelioration of the patients' psychiatric status occurred as early as within a week from the supplementary lithium therapy.