An 18-year-old male patient who had suffered from polyuria, nocturia and easy fatigabiity since childhood is described. A germ cell tumor in the suprahypophyseal region was diagnosed at the age of 13 years, and was treated by cranial irradiation. Growth retardation and other signs of hypophyseal deficiency successively occurred, and human growth hormone was administered for two years and five months from the age of 16 years until acute lymphoblastic leukemia developed. Adrianiycin, vincristine and prednisolone therapy induced complete remission, but the patient died of disseminated intravascular coagulation two months later. The relationship between the occurrence of leukemia and administration of growth hormone is discussed.