Six patients with Philadelphia-chromosome (Ph' +)-positive chronic granulocytic leukemia were transplanted from their HLA-identical siblings after conditioning with cyclophosphamide and 1'000 rad total body irradiation. All received cyclosporin-A for prophylaxis of Graft-versus-Host disease. All patients showed prompt engraftment and all are cytogenetically and clinically in complete remission. Two patients had transient mild signs of Graft-versus-Host-disease and one patient had unilateral facial nerve paresis of unknown origin. All are ambulatory and well 6-18 months (median 10 months) after transplantation.