Ten prepubertal children with stature at or below the 1st percentile for height and without growth hormone deficiency received 0.3 U recombinant growth hormone per kilogram daily for 2 years before puberty. Their growth velocity increased from 4 +/- 0.3 cm/yr before treatment to 10.7 +/- 0.6 and 8.8 +/- 0.6 cm, respectively, during the first and second years of treatment, and then remained at 5.7 +/- 0.7 cm the year after the end of growth hormone administration. This resulted in a near normalization of adolescent height. Bone maturation paralleled chronologic age, and therefore the expected final height of the children increased by approximately 10 cm. Administration of growth hormone induced a reversible hyperinsulinemia, with moderate and transient changes in glucose metabolism. A prospective, randomized study, including an untreated cohort, will be needed to confirm the effects on final height and to determine the magnitude of the response in familial short stature.