Mechanism of allograft rejection for the heart and, lung; late chronic effects of rejection, such as graft coronary, atherosclerosis in the heart and bronchiolitis obliterans in the, lung; treatment of rejection, including pharmacologic agents, total, lymphoid irradiation, and the induction of tolerance in fetal, animals; clinical studies include the results of lung and heart-lung, transplantation, modification of immunosuppressive protocols, and, factors contributing to late chronic rejection.