In order to improve the results of functional surgical procedures on the esophagus, the authors, after a number of experimental studies, proposed the use of intraoperative esophageal manometry (IEM). The technique was performed for the first time in 1972. IEM has been employed in the course of Heller's cardiamyotomies and Nissen-Rossetti (N-R) fundoplications, respectively, to document the ablation of the lower esophageal sphincter (LES) high-pressure zone (HPZ) and to calibrate the pressure of the fundal wrap between values ranging from 20 to 40 mmHg ('hypercalibrated Nissen'). This hypercalibration resulted from the retrospective evaluation of a former series when, at the beginning of our experience, we used to calibrate the fundoplication to pressure values similar to those of a normal sphincter ('normocalibrated Nissen': 10-20 mmHg). This experience, in fact, was followed by a high rate of gastroesophageal reflux (GER) recurrence (28.5%) in the first 12 months after surgery. Since 1985 to date, IEM has been employed in the course of 309 functional surgical procedures on the esophagus. This paper, however, reports on 281 patients: 144 with achalasia treated with Heller's myotomy + Nissen-Rossetti fundoplication and 137 with gastroesophageal reflux disease (GER-D) submitted to Nissen-Rossetti fundoplication. Our data suggest that IEM can be a useful tool in the field of functional surgery of the esophagus, and its routine use seems to be able to improve the postoperative results. In this series, in fact, IEM was able to detect the persistence of an HPZ in 15.2% of apparently complete myotomies, all performed with the aid of intraoperative endoscopy. As regards the manometric calibration of the n-HPZ, our results seem to confirm the validity of the technique, yet some findings still remain unexplained: i.e. two patients with a hypotonic n-HPZ and GER recurrence and two with an n-HPZ, exceeding 20 mmHg with postoperative persistent dysphagia. Finally, we would like to emphasize that the concept of a 'hypercalibrated Nissen' contrasts with the 'floppy Nissen' of Donahue and DeMeester; our wrap is also loose around the esophagus and does not impair the esophagogastric transit.