Seventy-five diabetic male and female children and 75 matched controls were classified according to pubertal staging. Blood samples were assayed for gonadotropins and gonadal hormones. The ultimate adult height in diabetic patients was 5 cm less than that of controls. Almost all diabetic children had a retarded bone age. Levels of serum gonadotropins and gonadal hormones did not differ markedly between diabetic and healthy children. The delay in growth and maturation was not due to hormonal failure, but probably to chronic undernutrition of body cells and failure to utilize the amino acids for protein anabolism related to relative insulin deficiency.