The treatment of pituitary infantilism has been unsatisfactory in the past, since growth hormones of animal origin have been ineffective in the human. This failure of response has been attributed to differences in molecular weight and other physico-chemical characteristics between growth hormones of various species. In this study, human growth hormone, prepared by the method of Li from pituitaries obtained at autopsy, was administered to a female pituitary dwarf aged 11 years, 5 months. Metabolic balances were determined for an initial control period of seventeen days, followed by periods of five to ten days during which the hormone was given intramuscularly in doses of 5, 10, or 2.5 mg. daily. Nitrogen retention was demonstrated at all 3 dosage levels, but was most pronounced at the 5-mg. level. There was also some retention of sodium, potassium and phosphorus and a slight increase in the concentration of serum alkaline phosphatase. Calcium was excreted initially, but during longterm administration of the growth hormone calcium was retained. The fasting blood sugar level was unchanged and there was no glycosuria. The glucose tolerance curve was higher, but the effects seemed transient and were probably related to the dosage level. The only toxic effect noted was slight fluid retention, which occurred with the highest dosages and also seemed transient. These findings are in general agreement with those of workers using animal growth hormone and with those of other workers using human growth hormone. Whether or not human growth hormone is an effective anabolic agent in subjects with an intact pituitary is an important but unsolved question. Studies of long-term administration of this growth hormone with particular reference to its effect on height are in progress; initial observations indicate a satisfactory response of linear growth.