In two randomized double-blind controlled trials on 63 depressed female in-patients subject to recurrent affective disorder (bipolar and unipolar manic-depressive psychosis) lithium was shown to have major acute antidepressant effects. At the end of three weeks lithium produced more uniform improvement than did imipramine; lithium in combination with tryptophan (in the form of Optimax) was superior to tryptophan alone--the latter drug having no discernible antidepressant activity in this group of patients. Lithium did not produce an antidepressant effect until the second and third week of both trials.