To identify the best immunosuppressive protocol in a centre where five different regimens are employed, 227 consecutive renal recipients who were transplanted over a 2.5-year period were studied. The five different regimens employed were cyclosporin monotherapy, dual therapy (cyclosporin and prednisolone), triple therapy (cyclosporin, azathioprine, prednisolone), antithymocyte globulin (ATG) followed by dual therapy and ATG followed by triple therapy. Recipients were chosen for the different regimens according to HLA mismatch, positive donor crossmatch due to IgM, regraft and delayed graft function. The group with the lowest risk, cyclosporin monotherapy, had the highest acute rejection rate, with only 13% free of acute rejection (in comparison to triple immunosuppression, P = 0.024, chi-square test). The overall infection rate and graft success rate were similar between the different groups.