The frequency of transfusions and the development of HLA alloimmunization in the years 1986 and 1995, representing the 'transfusion era' and the 'erythropoietin era', have been compared. The introduction of erythropoietin was found to reduce the need for transfusion in haemodialysed patients on the waiting list from 65.2% to 5.7%. The elimination of transfusions resulted in a decrease in HLA immunization from 56.5% to 35%. In those patients who were still immunized, antibody production was probably caused either by immunomodulation or by transfusions given to treat complications. Erythropoietin could be used instead of transfusions in almost all cases, except for complications involving severe bleeding.