Since pretransplant blood transfusions have been shown to prolong the survival of kidney grafts, a new transfusion policy has been started in the frame of Swisstransplant. Before surgery all patients receive at least two and, if possible, five transfusions (whole blood or packed red blood cells). The present study includes 101 recipients of primary cadaver grafts. Of these, 41 were transfused regularly according to the new protocol, 46 had irregular transfusions because of therapeutic necessity, and 14 had no transfusion before grafting. The 1-year survival rate in pretransfused patients was over 70% as compared to 45% in the nontransfused group. There was no significant association with the number of transfusions, but a slight improvement in graft survival was seen in patients deliberately transfused when compared with those transfused because of severe anaemia. A delay of more than 3 months between the last transfusion and transplantation significantly decreased graft survival at 6 months (84 versus 58%; P less than 0.02). The occurrence of cytotoxic antibodies, both antiperipheral blood lymphocytes (PBL) and anti-B cell antibodies, was investigated in relation to the number of transfusions received. Broad-spectrum anti-PBL antibodies (greater than 50% of random panel) were found in 5 of 74 patients transfused according to the protocol (7%) and in 15 of 93 patients transfused for severe anaemia (16% P, not significant). Of 71 recipients followed up for 6 months, 15 (21%) produced anti-PBL antibodies with limited specificity (less than 50%), and 4 (6%) produced broad-spectrum antibodies. Anti-B cell antibodies (less than 50%) were produced in 21 of 64 patients (33%). Six patients (9%) had broad-spectrum activity. The occurrence of these antibodies was not associated with the number of transfusions received and did not significantly influence the graft survival at 6 months. The change in transfusion policy seems to have improved graft survival without producing strong presensitization in a prohibitive proportion of the patients on hemodialysis.