To ascertain growth and rehabilitation of children after transplantation, the North American Pediatric Renal Transplant Cooperative Study collected growth data on renal transplant recipients. From January 1987 through December 1990, a total of 1553 children with one or more transplants were entered into the study by its 75 participating centers. Of these, the first 300 children with a functioning graft and 2 years of linear growth data form the cohort for this study. For the total cohort of 300 patients, the mean (+/- SEM) baseline height z score was -2.41 +/- 0.09, and the change in z score determined after 2 years was 0.18 +/- 0.06 (p < 0.01). Children in the age group from birth to 1 year had the maximal deficit and had the maximal improvement in z score, gaining about 1 SD (p < 0.01). For the 2- to 5-year-old group, the change in z score was about 0.5 SD (p < 0.001). No improvement in z score was noted for children 6 to 17 years of age. Each increase in serum creatinine concentration of 90 mumol/L (1 mg/dl) was associated with -0.17 decrease in the z score (p < 0.001). Gender, donor source, history of previous transplantation, and prior dialysis were not associated with a significant change in the z score; thus the increased rate of growth during the first 2 post-transplantation years occurred mainly in subjects less than 6 years of age.