Since 1985 we have done intraoperative manometry in 54 patients operated for achalasia. Manometry allows the assessment of the completeness of the division of the high pressure zone and ascertain the length of fundoplication (Nissen) as well as its pressure. In 26 patients pH and manometric controls were done postoperatively. Absence of reflux was noted in all and the pressure level after operation was 12.53 +/- 4.94 mmHg. Pressure measurements were not different from those of a group of 15 healthy subjects (15.2 +/- 2.45 mmHg). Dynamic studies of the high pressure zone revealed a post-deglutition relaxation of 72.5 +/- 16.32% over the basal tone. We believe that intraoperative manometry is essential in the surgical treatment of achalasia as it allows a precise control of myotomy as well as the fashioning of a high pressure zone to avoid reflux.