Background Laparoscopic adjustable gastric bands (LAGB) are a safe and effective treatment for obesity. Conflicting data exist concerning their effect on the esophagus, gastroesophageal junction, and mechanism of action. These patients will increasingly require accurate assessment of their esophageal function. Methods Twenty LAGB patients underwent high-resolution video manometry with the LAGB empty, 20 under, 20 over, and at their optimal volume. Twenty obese controls were also studied. Effects on esophageal motility, the lower esophageal sphincter (LES), and the gastroesophageal junction were measured. Transit during liquid and semisolid swallows was assessed. Results The intraluminal pressure at the level of LAGB was a mean of 26.9 (19.8) mm Hg. This pressure varied depending on the volume within the LAGB and was separate to and distal to the lower esophageal sphincter LES. The LES was attenuated compared to controls (10 vs 18 mm Hg; pa??