Beside pulmonary function tests, other measures of cardiopulmonary fitness have been shown to be useful for preoperative risk stratification. Reduced values of carbon monoxide lung diffusion capacity and its predicted postoperative value have been reported to be associated with postoperative complications and mortality. The most widely used low-technology exercise tests, which include 6 minutes of walking and stair climbing, have been reported to be valid predictors of complications. Patients with an impaired performance at these tests need to undergo a formal cardiopulmonary test with measurement of maximum oxygen consumption at cycle-ergometry or treadmill. Functional algorithms have been proposed that incorporate all these tests, with the aim to assist in defining the surgical risk.