Pneumothorax was identified as a complication of endoscopic hernia repair in two patients with insufflation pressures of 15 mmHg and operating times exceeding 2 h. These patients also showed intraoperative perturbations in both oxygen saturation and end-tidal CO2 production, A prospective study was undertaken to determine whether similar complications would arise if preperitoneal insufflation pressures were limited to 10 mmHg, Postoperative chest x-rays were obtained on all patients to check for pneumothoraces, even clinically occult ones, Fifty patients were studied, with average operating times of 67 min. No patient demonstrated any hemodynamic or ventilatory changes, and none had any evidence of pneumothorax on x-ray, We conclude that these complications were not present when insufflation pressure was maintained at 10 mmHg and that routine x-ray is not warranted. Larger randomized trials of insufflation pressures are needed.