Preoperative evaluation of patients undergoing lung resection remains an interdisciplinary challenge. Despite substantial progress in anesthesiology, intensive care medicine and surgery, mortality of patients undergoing pneumonectomy remains high at 5-9%. Guidelines were developed to identify patients with an increased perioperative risk for morbidity and mortality. These guidelines are focused around the forced expiratory capacity (FEV) measured by spirometry, following further investigations in patients with limited FEV(1). Extended testing includes measurement of the diffusion capacity, calculation of postoperative predicted values of lung function and spiroergometry to determine maximal oxygen uptake. In this article the methods to measure parameters of lung function and gas exchange are described and evaluated in the context of the current guidelines.