Recent investigations have explored how analyses of genetic DNA from organ donors and recipients may be helpful during organ allocation so as to reduce graft rejection or improve dosing of immunosuppressive medications. This discussion reviews those data and the processes by which genetic coding controls the production of protein that is important in cellular structure and function during donor and recipient care. Changes in gene structure (polymorphisms or mutations) may occur spontaneously or as a result of cell interactions with environmental factors, and may be associated with recognized diseases or, potentially, could reduce or worsen graft rejection.