Pulmonary function tests were performed for 50 patients who were undergoing different laparoscopic surgical procedures. Measurements were made 1 to 2 h before, and 24 h after the operation. There was a highly significant reduction (p < 0.001) in forced vital capacity (-10.97 +/- 1.78), forced expiratory volume in the first second (-15.39 +/- 2.43), forced expiratory volume in the third second (-13.18 +/- 2.07), peak expiratory flow rate (-20.08 +/- 3.57), forced expiratory flow rate 25-75% (-21.45 +/- 3.57), and peak inspiratory flow rate (-14.97 +/- 5.81). These changes reflect a restrictive as well as an obstructive dysfunction. Explanations have been proposed for these changes. The pulmonary function changes were found to be more pronounced with upper abdominal procedures, where the laparoscopic ports were placed in the upper half of the anterior abdominal wall, than with lower abdominal and pelvic laparoscopy, where the ports were placed in the lower half. However, the differences between these two groups did not reach the level of statistical significance for any of the tests. The duration of pneumoperitoneum proved to have a minimal influence on the changes in the first three functions, and almost no influence on the last three. The findings of this study verify the safety of laparoscopic surgery concerning pulmonary functions, irrespective of the site of ports and the duration of pneumoperitoneum.