1. The carbohydrate metabolism, as tested by the blood sugar tolerance curves, was studied in 116 psychotic patients. These include: Merergasia (psychoneurosis) 31 cases; thymergasia (manic-depressive psychosis) 50 cases, out of which six were in the manic state; parergasia (schizophrenia) 28 cases; anergasia (organic psychosis) 7 cases.2. The blood sugar curves were evaluated, first, by the intensity of the alimentary hyperglycemia (following the ingestion of 50 gm. of glucose); second, by the extension of the glycemic reaction over a two-hour period (hyperglycemic index) ; and third, by both the height and extension of the curve combined (hyperglycemic area).3. Abnormal curves were obtained in each psychotic group: In merergasia, 64 per cent; in hypothymergasia, 72.9 per cent; in parergasia, 60.7 per cent, when the curves were evaluated by the climax of the hyperglycemia. When estimated by the hyperglycemic area, the values were 62.5 per cent, 79.2 per cent, and 72.7 per cent, respectively; in anergasia, 100 per cent, judged by both methods of evaluation.4. The abnormal curves show similar characteristics in the four psychotic reaction types under consideration. In each of them the following three types of curves were found to be representative:(i) High and broad curves; (2) curves in which the hyperglycemic peak is moderately high but the glycemia remains above the fasting level two hours after glucose was taken; (3) curves in which the markedly high hyperglycemic reaction goes together with the return of the glycemia to the fasting level at the end of the two-hour period after the administration of glucose.5. It is believed that the apparently similar disturbance of the carbohydrate metabolism in the different psychotic reaction types may be related to a common denominator, that is, affective disorder.6. Thus, the abnormal blood sugar curves in our patients are considered as physiological accompaniments of psycho-biological reactions.