One hundred and nine out of one hundred and twenty-two cases of endogenous depression were followed-up after their index diagnosis 3-13 years earlier. No recurrence occurred in 28 cases. Forty-two cases turned out to be bipolar and 21 remained unipolar. Manic episodes outnumbered the depressive ones. The change of polarity from depression to mania occurred within three years after the initial depression, though in others the shift occurred between three years and twelve years. The number of episodes of depression before the onset of mania varied from 1 to 3. While the onset of depression before the age of 40 years predisposed to recurrences, there was risk of chronicity in those patients who developed the illness after 40.