Background: In a high proportion of patients with symptomatic gastroesophageal reflux disease, 24 h esophageal pH monitoring is normal. Aim: To study esophageal motility in patients with symptomatic gastroesophageal reflux disease and normal 24 h esophageal pH monitoring. Patients and methods: Fourteen patients (12 women, aged 28 to 74 years old) with esophageal reflux disease and normal 24 pH monitoring and 14 asymptomatic controls (8 women, aged 19 to 69 years old), were studied. Symptoms were evaluated using an analog scale and all subjects underwent a barium meal, upper gastrointestinal endoscopy and a standard esophageal manometry. Results: Lower esophageal sphincter was normal in 11 patients, hypotonic in one and displaced to the thorax in two. Esophageal wave amplitude was lower in patients than in asymptomatic controls (10 to 50 and 13 to 70 mm Hg respectively). The proportion of hypotonic waves was Grade I and II in seven patients, Grade III in three and grade IV in four cases. Four patients had localized aperistalsis (that can be considered normal) and four had more severe forms of aperistalsis, along with severe hypotonia. Conclusions: Patients with gastroesophageal reflux disease without alterations in 24 h pH monitoring, have alterations in esophageal motility (Rev Méd Chile 2000; 128: 1237-44)