Objective: The aim of this study was to demonstrate that the postoperative recovery of respiratory muscle strength is better in patients who undergo video-thoracoscopy than in patients who undergo transaxillary thoracotomy or posterolateral thoracotomy. Design: Randomized controlled trial with three parallel groups. Study population: Eligible patients had undergone wedge resection for lung biopsy in interstitial lung disease or in pulmonary nodule. Twenty-four patients were randomly assigned to one of the three thoracic procedures: eight in the videothoracoscopy (VT) group, eight in the transaxillary thoracotomy (TT) group, and eight in the posterolateral thoracotomy (PLT) group. Measurements: The postoperative respiratory muscle strength was assessed by maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) measured by mouth pressure. Measurements were made the day before the operation and 2, 4, and 30 days after the operation. Changes in postoperative MIP and MEP were expressed as a percentage of preoperative values. Results: The three groups were comparable with respect to age, gender, comorbidity, preoperative spirometry, preoperative MIP, MEPand peak flow, and volume of lung tissue. At 2, 4, and 30 days after the operation, mean MIP were, respectively, 111 22%, 119 22%, and 124 22% in the VT group, 76 22%, 109 22%, and 127 22% the TT group, and 51 22%, 50 22%, and 77 22% in the PLT group ( p < 0.0001). At 2, 4, and 30 days after the operation, mean MEP were, respectively, 94 15%, 103 15%, and 105 15% in the VT group, 61 15%, 98 15%, and 126 15% in the TT group, and 62 15%, 75 15%, and 87 15% in the PLT group ( p < 0.05). Conclusions: Video-thoracoscopy allows better recovery of respiratory muscle function after surgery than posterolateral thoracotomy. However, at 4 and 30 days after surgery, video-thoracoscopy and transaxillary thoracotomy gave similar results of impairment of respiratory muscle strength.