There is a subgroup of patients with achalasia in which manometry shows elevated intraesophageal pressure, expressed by elevation of esophageal baseline relative to gastric pressure. The aim of this study was to determine the prevalence of elevated intraesophageal pressure in patients with achalasia and its relationship to clinical, radiographic, endoscopic, and other manometric findings. Manometric studies of 62 patients with achalasia were analyzed and elevated intraesophageal pressure was considered any positive elevation of esophageal baseline relative to gastric pressure. Multiple regression analysis was used to determine independent risk factors associated with elevated intraesophageal pressure. Elevated intraesophageal pressure was found in 32 patients (51.6%). Lower esophageal sphincter pressure was the only independent variable associated with elevated intraesophageal pressure (P = 0.0167). Mean lower esophageal sphincter pressure was significantly higher in patients with elevated compared to those with normal intraesophageal pressure (34 +/- 1.96 vs 26.5 +/- 1.73 mm Hg; P = 0.006). In addition, lower esophageal sphincter pressure had a positive correlation with intraesophageal pressure (r = 0.49, P < 0.001). Conversely, no correlation was found between elevated intraesophageal pressure and various symptoms, disease duration, radiologic dilation, a finding of retained fluid during endoscopy, and esophageal length. We conclude that elevated intraesophageal pressure is a common manometric finding in patients with achalasia, with a prevalence of 51.6%, and is associated with significantly higher lower esophageal sphincter pressure.