Antibodies in the blood of a kidney transplant recipient can provide a barrier to transplantation, which is additional to the usual possibility of cellular rejection. The antibodies most frequently encountered are ABO (blood group) and human leucocyte antigen (HLA) (tissue-type) antibodies. About 250 living donor transplants each year in the United Kingdom have been stopped because of an antibody barrier. It is now possible to offer a choice of treatment modalities to these people, including exchange transplantation and antibody-incompatible transplantation. It is likely that both schemes will complement each other and both are available in the United Kingdom.