<p><b>OBJECTIVE</b>To evaluate and compare the value of cardiopulmonary exercise test and conventional pulmonary function tests in the prediction of postoperative cardiopulmonary complications in high risk patients with chest malignant tumors.</p><p><b>METHODS</b>From January 2006 to January 2009, 216 consecutive patients with thoracic malignant tumors underwent conventional pulmonary function tests (PFT, spirometry + DLCOsb for diffusion capacity) and cardiopulmonary exercise test (CPET) preoperatively. The correlation of postoperative cardiopulmonary complications with the parameters of PFT and CPET were retrospectively analyzed using Chi-square test, independent sample t-test and logistic regression analysis. The P value < 0.05 was considered as statistically significant.</p><p><b>RESULTS</b>Of the 216 patients, 57 did not receive operation due to advanced stage diseases or poor cardiopulmonary function in most of them. The remaining 159 underwent different modes of operations. Thirty-six patients (22.6%) in this operated group had postoperative cardiopulmonary complications and 10 patients (6.3%) developed operation-related complications. Three patients (1.9%) died of the complications within 30 days postoperatively. The patients were stratified into groups based on V(O(2)) max/pred (≥ 65.0%, < 65.0%); V(O(2)) max×kg(-1)×min(-1) (≥ 20 ml, 15 - 19.9 ml, < 15 ml) and FEV1 (≥ 2.0 L, 1.2 - 1.99 L, < 1.2 L) according to the criteria in reported papers. There was statistically significant difference among these groups in the parameters (P < 0.05), the rates of postoperative cardiopulmonary complications were much higher in the groups with poor cardiopulmonary function (V(O(2)) max/pred < 65.0%; V(O(2)) max×kg(-1)×min(-1) < 15 ml or FEV1 < 1.2 L). It was shown by logistic regression analysis that postoperative cardiopulmonary complications were significantly correlated with age, associated diseases, poor results of PFT or CPET, operation modes and operation-related complications.</p><p><b>CONCLUSIONS</b>FEV1 in spirometry, V(O(2)) max×kg(-1)×min(-1) and V(O(2)) max/pred in cardiopulmonary exercise test can be used to stratify the patients' cardiopulmonary function status and is correlated well with FEV1. V(O(2)) max×kg(-1)×min(-1) is the best parameter among these three parameters to predict the risk of postoperative cardiopulmonary complications in patients with chest malignant tumors and borderline cardiopulmonary function.</p>