Endoscopy is the standard test for postoperative control and sometimes the therapeutic procedure of failed antireflux procedures. The failed antireflux procedure has been associated with inadequate surgical technique. Currently there is not an objective method to evaluate the anatomy of the initial funduplication to prevent complications. We propose intraoperative endoscopy (IOE) during laparoscopic antireflux procedures (LARP's) to confirm adequate surgical technique. HYPOTHESIS: IOE confirms adequate surgical technique in LARP's. METHODS: Patients with indications for surgical treatment of GERD undergoing LARP in a private hospital setting in Mexico City from July 1999 to June 2004. All patients had informed consent for the surgical as well as IOE. Patients undergoing open procedures will be excluded as well as reoperations for previous failed antireflux surgery. The endoscopist will perform IOEduring the dissection, wrap construction and suturing of the LARP. The findings will be recorded and communicated to the surgeon to determine if the technique needs correction. The final endoscopic result will be evaluated at the completion of the surgical procedure. RESULTS: A total of 300 patients were operated with IOE during the study, 23 were excluded from the study, 14 reoperations and 9 conventional laparotomies. From the 277 patients included, 178 (64.3%) were males and 99 (35.7%) females. Average age was 43.38±14.02 years (range 12-85). There were 71 (25.6%) Toupetand 206 (74.4%) Nissen fundoplications. The average operating time decreased from 97.7min in 1999 to 59.2min in 2004 (range 23-255). IOE determined correction of the technique in 77(27.79%) patients. Of these 68(88.3%) because of rotated and/or angled fundoplication,1(1.3%) rotation with a distended stomach, 1(1.3%) with a redundant gastric fundus, and 7(9.1%) required change in the type of fundoplication from a 360° to 270°because of stenosis of the gastroesophageal junction. There were up to 6 changes (average 1.69±0.96 times) in the positioning and/or suturing of the fundoplication to obtain the correct IOE findings. CONCLUSION: IOE can assist the surgeon during a LARP to perform an adequate fundoplication and prevent anatomic changes that can ultimately affect the outcome of the procedure. Further studies will determine if the rutine use of IOE during LARP can prevent postoperative complications and improve the outcome of the surgical treatment of GERD.