Successful transplantation depends on the minimization of immunological differences between the donor and recipient tissues. These differences are based on polymorphisms of the human major histocompatibility complex and play a key role in determining the acceptance or rejection of allografts during transplantation. This important work describes methods for the investigation of these polymorphisms at the gene and protein levels and their application to the clinical transplantation of human organs and bone marrow. There is currently no other text available covering these up-to-date serological and molecular techniques in this area of immunogenetics, despite their importance to fundamental research, clinical practice and forensic medicine.