Esophageal achalasia is the most common primary esophageal motor disorder. Laparoscopic Heller's myotomy combined with fundoplication represents the treatment of choice for this disease, achieving good results in about 90% of patients. However, about 10% of treated patients refer persistent or recurrent dysphagia. Many Authors showed that this failure rate is related to inadequate myotomy.To verify, from experimental to clinical study, the modifications induced by Heller's myotomy of the esophago- gastric junction on LES pressure (LES-P profile, using a computerized manometric system.From 2002 to 2010 105 patients with achalasia underwent laparoscopic calibrated Heller myotomy followed by antireflux surgery. The calibrated Heller myotomy was extended for at least 2.5 cm on the esophagus and for 3 cm on the gastric side. Each step was evaluated by intraoperative manometry. Moreover, intraoperative manometry and endoscopy were used to calibrate the fundoplication.The preoperative mean LES-P was 37.73 ± 12.21. After esophageal and gastric myotomy the mean pressure drop was 21.3% and 91.9%, respectively. No mortality was reported.Laparoscopic calibrated Heller myotomy with fundoplication achieves a good outcome in the surgical treatment of achalasia. The use of intraoperative manometry enables an adequate calibration of myotomy, being effective in the evaluation of the complete pressure drop, avoiding too long esophageal myotomy and, especially, too short gastric myotomy, that may be the cause of surgical failure.