Since August 1978 prospective HLA-DR typing has been performed in 157 donor-recipient pairs. All recipients received pretransplant blood transfusions. This study shows that HLA-DR matching can significantly improve the survival of cadaveric kidney allografts, even in polytransfused recipients. Patients receiving kidneys with no HLA-DR incompatibilities have a one-year graft survival of 97%, versus 86% for recipients with 1 HLA-DR incompatibility and 73% for recipients with 2 HLA-DR incompatibilities. The cumulative dose of corticosteroids during the first year after transplantation is significantly lower in patients with no DR-incompatibilities. HLA-A and B matching have no additional effect on graft survival.