Background/aims: The necessity of manometric evaluation before fundoplication in patients with gastroesophageal reflux disease is still a matter of debate. However, misdiagnosis can be responsible for postoperative problems. We aimed to evaluate the necessities of manometry and pH-metry before fundoplication in order to prevent possible complications after surgery. Methods: Between 1997 and 2004, 259 consecutive patients who referred to our laboratory with a diagnosis of gastroesophageal reflux disease and request for manometric test before surgery were evaluated retrospectively. Manometric analysis was performed in all patients and 24-hour ambulatory pH-metry in 91 of them. Results: The mean age of the patients was 42.6 +/- 13 years and 51% were female. While 102 (39.4%) of the patients had normal esophageal motility, 122 (47.1%) had gastroesophageal reflux-related dysmotility (22% with ineffective esophageal motility, 25.1% with hypotensive lower esophageal sphincter). Primary esophageal motility disorders were detected in 29 (11.2%) patients (4 achalasia, 24 uncoordinated contractions and 1 nutcracker esophagus). Six patients had secondary dysmotility caused by scleroderma. Pathologic reflux was detected in 54 (59.3%) patients in whom pH-metry was performed. Conclusions: Our results support that manometty and pH-metry must be performed before surgery in gastroesophageal reflux disease.