Epididymal adipose tissue obtained from hypophysectomized rats responds to the addition of growth hormone in vitro with increased glucose uptake, oxidation to CO2 and conversion to fatty acids. As little as 0.01 μg/ml of bovine growth hormone was found effective in this regard. In all, 10 growth hormone preparations from 5 species of animals were tested and all were found to be active. Growth hormone also produced these effects when adipose tissues from normal rats fed a high carbohydrate, fat-free diet were tested, but was ineffective on adipose tissue from normal rats fed the standard laboratory ration. The increase in glucose utilization was accompanied by a proportionate increase in appearance of both carbon 1 and carbon 6 in CO2. Corticotropin and thyrotropin, while stimulating glucose uptake and oxidation to CO2, failed to increase the incorporation of glucose carbons into fatty acids. Of the other pituitary hormones tested only oxytocin and certain prolactin preparations caused changes in glucose metabolism which were comparable to those caused by growth hormone. (Endocrinology76: 216, 1965)