Laparotomy causes a significant reduction of pulmonary function, and atelectasis and pneumonia occur after open cholecystectomy. In this prospective, randomized study, we evaluated the hypothesis that pulmonary function is less restricted after laparoscopic cholecystectomy (LC) than after open cholecystectomy (OC). Sixty patients underwent laparoscopic (n = 30) or open (n = 30) cholecystectomy. The two groups did not differ significantly in age, sex, intraoperative findings, and preoperative pulmonary function. Pulmonary function tests, arterial blood-gas analysis, and chest radiographs were obtained in both groups before operation and on postoperative day 1. The forced expiratory volume in 1 s (mean +/- SD values; OC, 1.49 +/- 0.77 L/s; LC, 2.33 +/- 0.80 L/s; p > 0.0001) and the forced vital capacity (OC, 2.40 +/- 0.66 L; LC, 2.93 +/- 1.05 L; p > 0.01) were more suppressed in patients having OC than in those having LC. Similar results were found for the peak expiratory flow (OC, 3.51 +/- 1.35 L/s; LC, 4.27 +/- 1.66 L/s; p > 0.05), expiratory reserve volume (OC, 0.73 +/- 0.34 L; LC, 0.92 +/- 0.43 L; p > 0.05), and the midexpiratory phase of forced expiratory flow (FEF25-75) (OC, 1.45 +/- 0.54 L/s; LC, 1.60 +/- 0.73 L/s; NS). Laparoscopic cholecystectomy was associated with a significantly lower incidence of (30 vs 70%) and less severe atelectasis and better oxygenation. Pulmonary function is better preserved after LC than after OC.