The results of 6 months to 8 years of treatment of pituitary dwarfism in 1,959 patients in Japan were summarized. The data were based on the reports of the physicians treating the patients. Among the patients, 1,720 cases suffered from idiopathic pituitary dwarfism, 227 cases from secondary pituitary dwarfism, and 12 cases from unknown causes. Their initial age ranged from 9 months to 36 years old and their initial bone age ranged from 3 months to 15 years old. In most cases, a definite effect was observed. The effect was most remarkable during the initial 6 months and then declined gradually up to the fourth year. Males responded better than females. In younger and more immature patients, the effect was more remarkable. There were almost no side effects other than a few cases of impairment of capital femoral epiphysis.