To assess the effect of pretransplant blood transfusions on the outcome of cadaveric kidney transplantation, a single-centre analysis was performed of 171 patients randomly assigned to receive no pretransplant transfusion (n = 85) or to receive at least three random blood transfusions (n = 86). After transfusion 18 of the latter patients developed circulating lymphocytotoxic T-cell antibodies, but the sensitization was only transient. At the time of transplantation, none was still sensitized. In both groups 60 patients have been transplanted. Patient and graft survival rates were significantly higher in the transfused group than in the non-transfused group. In the non-transfused patients the higher mortality was due to complications related to repeated anti-rejection therapy. Non-transfused patients had more repeated acute rejection episodes than the transfused patients. The present study indicates that pretransplant blood transfusions still facilitate graft acceptance even in the setting of good HLA matching and with cyclosporine as the basic immunosuppressant. The risk of sensitization is very low.