The infraumbilical incision required for open repair of bilateral inguinal hernia with a giant prosthesis is associated with postoperative pain and respiratory impairment. The aim of this study was to evaluate the postoperative respiratory dysfunction after bilateral hernia surgery. Thirty-nine patients were randomized into two groups: open repair according to the Stoppa technique and laparoscopic extraperitoneal repair (TEPP). Respiratory function tests were performed before and 24 hours after surgery. The two groups were well matched for age, American Society of Anesthesiologists (ASA) risk score, type of hernia, and preoperative lung function. The postoperative forced vital capacity (FVC), peak expiratory flow (PEF), and forced expiratory volume in 1 second (FEV 1.0) were significantly altered in both groups. The PEF dropped 15% in both groups. The FVC dropped 22% after Stoppa versus 25% after laparoscopy (P = 0.7). The FEV 1.0 dropped 21% after Stoppa versus 9% after laparoscopy (P = 0.12). We conclude that laparoscopic preperitoneal and open bilateral hernia repair are followed by similar ventilatory dysfunction, although a trend toward better postoperative FEV 1.0 was noted after laparoscopy. This might play a role in selected patients with severe pulmonary limitations. Overall, the limited drop in pulmonary function following bilateral hernia repair under general anesthesia may serve to explain the low pulmonary morbidity that follows these procedures.