Growth retardation is common in children with chronic renal failure (CRF). To investigate the efficacy and safety of recombinant human growth hormone treatment in such children and in children after renal transplantation, 43 prepubertal children with CRF, and 30 prepubertal and 25 pubertal patients with a renal transplant were studied. Data are reported for 31, 26 and 17 of these patients, respectively. Median height velocity increased from 4.2 to 9.8 cm/year during the first year of treatment, and to 6.8 cm/year during the second year of treatment in the patients with CRF. In the prepubertal transplant group, median height velocity changed from 3.5 to 8.4 cm/year during the first year and to 5.4 cm/year during the second year. In the pubertal transplant group, median height velocity increased from 3.2 to 6.6 cm/year during the first year and was 4.5 cm/year during the second year. The gain in height SDS for the prepubertal children in both the CRF and transplant groups was approximately 1 SD over 2 years. Treatment was well tolerated, and renal function did not change significantly in any group.