Recombinant human growth hormone (rhGH) was administered to 13 pediatric renal allograft recipients, ages 7.6 to 17.7 yr, who were 14 to 92 months posttransplant and growth retarded as manifested by either a standard deviation (SD) more negative than -2.00 or a height velocity index of less than 25%. The rhGH was given either daily or thrice weekly (0.375 mg/kg/wk) for a period of 12 to 36 months. Growth velocity increased from 2.7 +/- 2.1 SD for the 12-month period before the initiation of treatment of 6.3 +/- 2.9 SD (P less than 0.00005) and 5.2 +/- 2.9 SD (P less than 0.02) after 12 and 24 months of treatment, respectively. Although individual recipients had improvement in their SD scores, the mean values did not increase despite the increased growth velocity. Except for a 0.5-yr increase over 24 months in two recipients, the bone age did not increase at a rate greater than the increase in chronologic age. Four rejection episodes occurred in two recipients during rhGH treatment--an incidence not greater than that which occurred during a comparable time interval before the initiation of treatment. The calculated creatinine clearance declined from 66 +/- 26 SD mL/min/1.73 m2 at the initiation of treatment to 55 +/- 30 SD mL/min/1.73 m2 at 24 months and 52 +/- 28 SD mL/min/1.73 m2 (P = not significant).(ABSTRACT TRUNCATED AT 250 WORDS)