BACKGROUND/AIMS: Ineffective esophageal motility (IEM) is a distinct manometric entity characterized by a hypocontractile esophagus. Recently, IEM replaced the nonspecific esophageal motility disorder (NEMD), and its associations with gastro-esophageal reflux disease (GERD) and respiratory symptoms are well known. We evaluated the relationship of IEM with GERD, and the diagnostic value of IEM for GERD. METHODS: We retrospectively analyzed recent 3-year (Jan. 1998-Sep. 2002) datas of esophageal manometry, acid perfusion test and simultaneous 24 hr-ambulatory pH-metry with manometry studies in 270 consecutive patients with esophageal and/or GERD symptoms. The prevalence of IEM in GERD group and non-GERD group, and the variables of pH-metry and manometry among esophageal motility disorders were compared. In addition, the sensitivity, specificity, positive predictive value, negative predictive value of IEM, esophageal symptom, and acid perfusion test for GERD were calculated. RESULTS: There was no significant difference in IEM prevalence rate between GERD group and non-GERD group. In addition, there was no significant difference in GERD prevalence rate and esophageal acid clearance in variety of motility disorder groups. Total percent time of pH <4 in IEM group did not show any difference when compared with other groups except in the achalasia group. In regard of diagnostic value to detect GERD, all positive results showed high specificity (97%) in IEM with esophageal symptom and positive acid perfusion test. CONCLUSIONS: The diagnosis of IEM using esophageal manometry in patients with various esophageal symptoms does not strongly suggest on association with GERD. However, IEM with concomitant esophageal symptoms and positive acid perfusion test has diagnostic values for GERD.