AbstractThe disappearance of3H‐corticosterone from the serum was measured in obese‐hyperglycemic mice and their lean litter mates of various ages. At 1 month of age the serum half‐life of the injected tracer was the same in the obese and lean animals. In the 2, 5 and 12 months old mice the tracer hormone disippeared faster in the obese mice than in their lean controls. The present results confirm that the previously observed enlargement of the adrenal cortex and the increased secretion of corticosteroids by adrenal glandsin vitroin fact indicate a considerably hyperadrenocorticism in the obese mouse. Furthermore, the difference in disappearance rate of corticosteroidsin vivobetween obese and lean mice approximately parallels the age variation of the other metabolic abnormalities of the syndrome suggesting that the hyperadrenocorticism is part of the multiendocrine disturbance which manifests itself as the obese‐hyperglycemic s