In more than 1,100 kidney transplants performed at a single center in 21 years a conservative approach to immunosuppressive therapy and HLA antigen matching has ensured high survival rates after both short- and long-term follow-up. 2. Retransplantation has been carried out in 16.6% of patients with transplant survival rates not differing significantly from those in first transplant recipients. 3. Living-related donor transplants accounted for only 7.9% of cases since 1982 and transplant survival was no different from HLA-A,B,DR-identical cadaver donor transplants. 4. Pretransplant blood transfusions were given to over 98% of recipients since 1982 and transplant survival in such CsA-treated patients was 10% higher than in the few nontransfused recipients. 5. By adopting a meticulous policy of pretransplant cytotoxic antibody screening and HLA antibody definition followed by careful pretransplant crossmatching using all available patient sera, accelerated transplant rejection has largely been avoided. 6. Monitoring of posttransplant recipient sera has shown that the appearance of cytotoxic antibodies leads to transplant failure and these antibodies are usually directed against HLA antigens mismatched between donor and recipient. 7. Matching for HLA antigens has a striking positive effect on transplant survival with more than 30% difference between the no mismatch and no match groups. Positive HLA matching effects on transplant survival were found in retransplants, highly sensitized recipients, male and female recipients, all ABO blood groups, and after long-term (20 years) follow-up.