Two-hundred three children 1 to 16 years of age received kidney transplants during a 20-year period, 100 from living donors and 103 from cadaver donors. The overall survival rate was 79%. Actuarial patient and kidney survival rates at 15 years were 79% and 52%, respectively, for recipients of living donor kidneys and 57% and 19%, respectively, for recipients of cadaver donor kidneys. One of two children who received transplants in 1964 was alive 20 1/2 years later. Twenty-nine children had kidneys that had functioned more than 10 years; their mean serum creatinine concentration was 1.7 mg/dL and 24 were fully rehabilitated. Eighteen were more than 2 SD below the mean height of normal children, however. Comparison of survival rates during successive 5-year intervals showed significant improvement in patient survival during the 20-year period and smaller improvements in kidney survival after 1979. Patient survival after living donor transplants during the last 10 years was 100%, and kidney survival during the last 5 years was 92%. Improvement was attributed to the effect of experience, as well as to changes in immunosuppressive therapy in 1972 and the introduction of donor-specific transfusions in 1978.