BACKGROUND: Postoperative loss of exercise capacity and pulmonary function is a major concern among lung cancer patients. In this study, the time for a stair-climbing to 12-m height was used to investigate whether preoperative chest 3D-computed tomography (CT) could be a useful tool for predicting postoperative variations in exercise capacity and pulmonary function. METHODS: Seventy-eight patients undergoing lobectomy for suspected stage I lung cancer were prospectively enroled. Preoperatively, lobe volume and low attenuation volume (LAV) were evaluated using the SYNAPSE VINCENT system. Preoperative data on stair-climbing time, spirometry and diffusing capacity of the lung for carbon monoxide (DLCO ) at baseline and 6-month postoperative data were used to evaluate variations in exercise capacity and pulmonary function. Maximal oxygen uptake (VO2 t) was evaluated based on the stair-climbing time. RESULTS: Significant differences in the variation of exercise capacity at 6 months postoperatively were found between the groups categorized by target lobe volume and LAV status: The large volume/LAV (+) group had a greater decline in VO2 t. Mean loss of VO2 t was -6.2%, -1.4%, -1.6% and -0.1% in the large volume/LAV (+), large volume/LAV (-), small volume/LAV (+) and small volume/LAV (-) groups, respectively. The large volume/LAV (-) group had a greater decline in forced expiratory volume in 1 s. The small volume/LAV (+) group showed a reduced decline in the DLCO . CONCLUSIONS: Analysis of chest 3D-CT scans is a potential tool for predicting the loss of exercise capacity and pulmonary function after lung lobectomy.