Purpose: Laparoscopic gastric banding has become a routine procedure in the treatment of morbid obesity. At present there is no accepted method to standardize the quantity of postoperative band filling. Gastric banding causes an outflow obstruction regulated by band adjustment. In this study the dependence of secondary peristaltic waves on outflow obstruction was investigated with a new method of in vivo intraband manometry. Patients and Methods: 30 patients (mean age 37.7 years; mean BMI 44.2) were included in the study. In all patients a Swedish adjustable gastric band (SAGB) was implanted in pars flaccida technique in a standardized way. According to international standards the first band filling was performed six weeks postoperatively by 0.5 ml steps. The technical equipment for intrasystemic band manometry consists of a Hoover needle which is placed in the port. Using a transducer (Edwards, Truwave PX-600red) manometric waves at the site of the band can be visualized and recorded (Datex-Ohmeda, S/5-Collect, Vers.4.0). Patients were asked to perform 15 ml wet swallows. The manometric profile is dependent on the outflow obstruction caused by intraband filling. The number of secondary waves and the pressure rises inside the band at each adjustment were investigated. Obstruction of the band was defined when secondary waves after a wet swallow occured for more than two minutes. Results: Depending on the fill volume of the band, different increases of pressure and the appearance of secondary peristaltic waves triggered by wet swallows were recorded. Obstruction of the band occured at a mean volume of 7.3 ml, in each patient an occlusion in barium x-ray control was then observed. At a mean fill volume of 6.3 ml a mean number of secondary waves of 1.4 occured. The SAGB has a range of 1.5 ml between no secondary peristalsis and total occlusion of the band. Conclusion: Secondary esophageal peristalsis has a strict dependence on the amount of outflow obstruction. Intraband pressure measurement is an encouraging new access to gastric banding. It appears to be a feasible method to control band adjustment without need for x-ray studies in low pressure bands.