HIGH responses to insulin tolerance tests (ITT) were studied in 13 hospitalized depressed patients. Five failed to secrete HGH adequately, with maximal responses of 5 ng/ml or less despite drops in blood glucose levels of more than 50%. In four of the five deficient HGH responses persisted after clinical recovery. In contrast, all 23 nondepressed age-matched subjects had adequate HGH responses (P < 0.004). In the depressives, the deficient responses could not be related to psychological characteristics or to plasma cortisol and glucose responses to ITT but tended to correlate with high endogenous cortisol production rates (above 25 mg/gm of creatine). The depressed group's hypoglycemic response to insulin was less during illness than after recovery (P < 0.01). This relative insulin insensitivity appeared unrelated to the other endocrine responses. Possible mechanisms for the abnormal endocrine responses are discussed.