BACKGROUND: The application of CPAP has been used to minimize postoperative pulmonary complications after lung resection surgery. The aim of this study was to quantify both the CPAP effects upon lung function and functional capacity in early postoperative lung resection, as well as to evaluate if CPAP prolongs air leak through the chest drain. METHODS: Thirty patients in the postoperative period of lung resection were allocated into 2 groups: an experimental group, consisting of 15 patients who underwent a 10 cm H 2 O CPAP, and a 15 patient control group, who performed breathing exercises. Arterial blood gas analysis, peak expiratory flow (PEF), respiratory muscle strength, spirometry, and 6-min walk test (6MWT) were assessed in the preoperative period, and repeated postoperatively on the first and on the seventh day (6MWT was repeated only on the seventh day). RESULTS: Significant increases in PEF, muscle strength, and FEV 1 between the first and seventh postoperative day were observed, both in the experimental and in the control group, whereas FVC and P aO 2 increased significantly between the first and seventh postoperative day only in the experimental group. The average loss in 6-min walk distance (6MWD) from preoperative to postoperative day 7 in the experimental group was significantly lower than in control group. When comparing the 2 groups, only 6MWD was statistically different (P < .001). There was no air leakage increase through the drain with the early use of CPAP. CONCLUSION: When compared to breathing exercises, CPAP increases the 6MWD in postoperative lung resection patients, without prolonging air leak through the chest drain.