The majority of children with renal allografts have diminished growth and reduced final height. Impaired allograft function and glucocorticoid treatment are the main contributing factors. Since recombinant human growth hormone (rhGH) treatment was able to counteract the growth depressing effects of glucocorticoids in experimental uremia, an open-labeled prospective study in 17 short children with renal allografts was designed to investigate the efficacy of rhGH therapy (30 IU/m2/week) with special emphasis on the safety regarding graft function and carbohydrate metabolism. Height velocity in prepubertal children (N = 10) increased from baseline median 2.2 cm/year to 7.9 cm/year after one year (P < 0.01), 7.2 cm/year after two years (P < 0.01), and 5.5 cm/year (P < 0.05) after three years of rhGH therapy. This resulted in a normalization of height in three out of seven patients after two years and in three out of five after three years of therapy. Growth stimulation in pubertal children was less consistent. Bone maturation paralleled chronological age. The effect of rhGH treatment on longitudinal growth may be partially attributable to the improved ratio between the serum concentration of the insulin-like growth factor (IGF)-I and its major binding protein (BP) IGFBP-3 leading to a normal IGF bioactivity. The incidence of acute rejection crises in the study group (corrected for time after grafting) did not differ from that of untreated retrospective "controls" (0.10 vs. 0.12 episodes per patient and year). No systematic effect of rhGH on glomerular filtration rate assessed by repeated inulin and creatinine clearances was noted.(ABSTRACT TRUNCATED AT 250 WORDS)