The aim of this study was to determine the role of physiological measurements in the evaluation of postoperative risks before lung cancer surgery. Spirometry and ABG were performed for all patients with NSCLC before operation. Diffusion test and CPET were performed to patients with moderate-high risk for operation and the patient who required pneumonectomy. Postoperative complications, mortality and duration of stay in ICU and hospital were recorded.115 NSCLC patients who had limited lung capacity(22F,93M) with a mean age of 62.37±10.11 were included prospectively between Jan2015-Dec2018. 54(46.9%) patients were accepted as medical inoperabl according to clinical and physiological assessments by algorithm of the 2013ACCP Evidence-Based Clinical Practice Guideline.79cases had COPD. Operation performed to 61 patients(4 wedge resection, 1 segmentectomy, 26 lobectomy, 4 bilobectomy, 26 pneumonectomy). FEV1(L), FVC(L), DLCO(%pred), VO2L/min, VO2/kg(mL/kg/min) values were lower in non-operated group than operated group(p=0.001, p=0.01, p=0.01, p=0.02, p=0.04 respectively). Three patients died during follow-up. FEV1(L), FVC(L), VO2/kg(mL/kg/min), VO2L/min, VO2L/min(%pred) and Work values at peak exercise were lower in mortality group. Post-operative complications were pneumonia in 9 patients, prolonged air leak in 7, bronchopleural fistula in 3, chylous drainage in 1 and rethoracotomy in 1 patient; cardiac complications were arrythmia in 6 and heart failure in 1 patients. PFTs and CPET results were not correlated with complication rates and duration of stays in ICU and hospital. Postoperative complications and mortality can be reduced by evaluation of preoperative PFTs and CPET.