The treatment of choice for end-stage renal failure within the first year of life is controversial. Between September 1970 and February 1991, we performed 28 kidney transplants (27 primary, 1 retransplant, 23 living donor, 5 cadaver) in infants less than 1 yr of age (mean, 7 +/- 2 months; range, 6 wk to 12 months). The 1-yr patient survival rate for living donor recipients was 100% versus 20% for cadaver recipients (P = 0.0001). The 1-yr graft survival rate for living donor recipients was 96% versus 20% for cadaver recipients (P = 0.001). The 1-yr patient survival rate for cyclosporin A (CSA) recipients (N = 12) was 100% versus 75% for non-CSA recipients (P = 0.03). The 1-yr graft survival rate for CSA recipients was 92% versus 75% for non-CSA recipients (P = 0.08). There was no difference in the number of rejection episodes or serum creatinine levels in CSA versus non-CSA recipients. Compared with pretransplant values, the mean posttransplant standard deviation scores (SDS) for height (N = 18), weight (N = 22), and head circumference (N = 8) improved: height SDS from -1.9 to -1.5 (not significant); weight SDS from -2.5 to 0.6 (P less than 0.0005); head circumference SDS from -2.0 to -0.7 (P = 0.01). Because no other renal replacement therapy can match these results, we conclude that renal transplantation is the treatment of choice for infants with end-stage renal failure.