The fasting lower esophageal sphincter pressure of 18 normal volunteers was compared to 22 patients with symptoms and objective evidence of gastroesophageal reflux. Lower esophageal sphincter pressure was measured by rapid pull-through using an 8-lumen radially perfused catheter that sampled pressure every45 degrees around the circumference of the sphincter. The 22 reflux patients were subdivided for analysis into two groups, those with an acute inflammatory infiltrate on biopsy and those without inflammation. Those patients without inflammatory esophagitis had normal sphincter pressures. Those with a definite inflammatory infiltrate had pressures significantly less than normal. The least reliable separation between normals and those with inflammatory esophagitis occurred in the anterior orientations. We conclude that while basal lower esophageal sphincter pressure measurement may identify patients with reflux and inflammatory esophagitis, it is of no help in identifying those patients with reflux unassociated with inflammation. Decreased basal fasting LESP does not appear to be the most important primary determinant of gastroesophageal reflux.