We performed oral glucose tolerance tests (oGTTs) on 15 children who had functioning renal allografts received greater than or equal to 18 months previously, had adequate renal function, and had heights greater than 2.5 SD below the mean height for age. Three of the children had impaired glucose tolerance; their mean glucose levels during the last 2 hours of the oGTT were higher (p less than 0.05) than published control values. Integrated glucose concentrations correlated inversely with the prednisone dose on the first day of an alternate-day dosage schedule (R2 = 0.383) and directly with adiposity (partial R2 = 0.322). The integrated insulin concentration correlated directly with the prednisone dose on day 1 of an alternate-day regimen (R2 = 0.355) and with age (partial R2 = 0.163). In 10 children with renal transplants who had been treated with growth hormone for greater than or equal to 6 months, the mean fasting glucose concentration, integrated glucose concentration, and integrated insulin concentration during the oGTTs obtained after 6 months or 12 months of growth hormone treatment were not significantly different (p greater than 0.05) from values measured before the treatment. We conclude that increased integrated concentrations of both glucose and insulin during oGTTs in children with renal allografts correlate with the dose of prednisone administered on the first day of an alternate-day schedule, with age, and with adiposity index. Growth hormone treatment of children with renal allografts who are growing poorly does not significantly affect glucose metabolism as assessed by oGTT.