Adult male and female rats force-fed a high carbohydrate liquid diet consistently developed hyperglycemia and glycosuria while receiving both ACTH and growth hormone. No or inconstant glycosuria resulted on treatment with either hormone alone unless excessive diet volumes were fed. In 1 rat on a fixed dose of ACTH, glycosuria appeared to vary directly with the dose of growth hormone, whereas the reverse did not appear to be true. The significance of these results is discussed with regard to the comparative roles of the pancreas, adrenal cortex and the capacity for growth in determining the diabetogenic effect of growth hormone in the rat. A level of adrenal activity high enough to prevent the full expression of the growth response to growth hormone may be necessary before a diabetogenic effect of growth hormone becomes apparent, while the high functional reserve of the pancreas may be responsible for the failure to develop permanent diabetes.