Traditional pulmonary function tests are inadequate to explain the presence of dyspnea in certain patients. Measurement of various cardiorespiratory parameters during exercise may reveal otherwise unsuspected abnormalities. Exercise testing is also useful in distinguishing pulmonary from cardiac mechanisms of exercise limitation and in the evaluation of disability. The Exercise Physiology Laboratory has investigated the mechanisms of pulmonary dysfunction in asbestos-related lung and pleural disease, sarcoidosis, genetic storage diseases, and other pulmonary disorders. This work involves defining normal values for exercise parameters, and analyzing physiologic correlates of dyspnea. The laboratory has participated in a multicenter cooperative trial using preoperative exercise testing as a prognostic indicator for patients with lung cancer and is now engaged in studies of transplantation patients.