Organ transplantation has been one of the major medical achievements of the twentieth century. Transplants have saved the lives of countless patients with failure of one, or more, of their vital organs and have returned most to a happy and productive existence. The lung proved to be one of the most difficult organs to transplant and clinically successful lung transplantation was first achieved two decades after the first renal allografts were performed. The results of lung transplantation have steadily improved and the procedure is now accepted as a standard therapy for patients with advanced parenchymal or vascular pulmonary disease. This success has produced a growing population of lung transplant recipients but has also highlighted the problems and limitations of lung transplantation that now represent challenges for the twenty-first century.

Currently, the potential long-term benefits of lung transplantation are reduced by the frequent occurrence of bronchiolitis obliterans, which leads to progressive dysfunction of the pulmonary allograft and eventually to respiratory failure. Our understanding of the pathogenesis of this condition remains limited but there is some hope that newer approaches to pharmacological immunosuppression, including the use of drugs with antiproliferative properties, together with more effective prophylaxis against infection may reduce the impact of this condition. The burden of long-term pharmacological immunosuppression (infection and malignancy), as well as side effects of individual immunosuppressive drugs, are other important problems faced by transplant recipients. Progress has been made in this area through the more effective use of drug combinations to minimize the side effects of individual agents, the introduction of agents with better side effect profiles, and prophylaxis against some specific complications, such as infection with Pneumocystis or cytomegalovirus and against corticosteroid-related osteoporosis.