Observations on body weight gain, blood glucose levels, and responses to a glucose challenge in ob/ob mice adrenalectomized at five months of age, demonstrate that removal of the adrenals of older mice retains the potential to lower serum glucose levels and depress body weight gain seen in young ob/ob mice adrenalectomized at two months of age. These findings suggest that the adrenals continue to play a role in body weight gain and hyperglycemia of the ob/ob mouse up to five months of age.