The effect of body weight excess and hyperlipidemia on stimulated growth hormone (GH) secretion and serum somatomedin activity (SSA) has been investigated. Among 40 obese men gradually impairment of GH secretory response during the insulin hypoglycemia test was shown. Propranolol-L-DOPA administration elicited satisfactory GH secretory response only in the subgroup of patients with the mild weight excess. SSA was found to be in the normal range among the whole group of obese patients, however, it was significantly depressed in subjects with average weight excess higher than 100%. Obese men with hypertriglyceridemia and hypercholesterolemia presented low SSA even when their weight excess was relatively moderate, i.e., 52% and 57%, respectively.