Ninety two out of one hundred cases of major depressive disorder were followed up for a period of 5 to 10 years after the index diagnosis. 36.6 per cent of the cases, had no recurrence. Out of the 63.4 per cent of the cases who had recurrences, 37.8 per cent cases turned out to be having bipolar affective disorder and remaining 25.6 per cent had major depressive disorder, recurrent type. The change of polarity from major depressive disorder to bipolar affective illness occurred within three years after the initial depressive episode in 77 per cent of the cases. The number of depressive episodes before I he onset of mania, was one in 63.0 per cent of the cases; two in 33.3 per cent and three in 3.7 per cent. 31 cases of bipolar affective disorder had a total of 152 recurrences, comprising 97 manic and 55 depressive episodes, the average being 4.9. The total number of episodes in 21 cases of major depressive disorder, recurrent type, were 73 yielding an average of 3.4, significantly less than those of bipolar affective illness cases. 2.2 per cent of the cases had successfully committed suicide.