Esophageal manometric study has gained tremendous popularity over the past decade. However, the contribution of this diagnostic technology has not been critically evaluated. The purpose of this report is, therefore, to determine how frequently esophageal manometry alters the clinical diagnosis and treatment and to assess the cost of new information. The patients reviewed in this report consisted of 363 consecutive referrals. Each completed a questionnaire, had an esophagogram, and underwent an esophageal manometric study for the evaluation of dysphagia, heartburn, and/or chest pain of unexplained etiology. To determine the clinical contribution of manometry, diagnoses before and after the study were compared. On the basis of symptoms and radiologic data, specific clinical entities were diagnosed in 36 patients. Manometric study did not confirm the diagnosis of achalasia in four of the 27 patients referred with this diagnosis and resulted in 19 additional specific diagnoses. Manometry changed the course of treatment in 14 cases, eight additional patients with achalasia received treatment, and four false-positive patients were spared inappropriate treatment. Moreover, two patients with simultaneous esophageal motor disorder and chest pain were spared further investigation. It is concluded that esophageal manometry altered the clinical diagnosis in 6% and changed the course of treatment in 4% of the population studied. Esophageal manometry is beneficial in patients with chest pain, dysphagia, and those in whom diagnosis of achalasia is suspected, but is of little benefit in patients with chronic heartburn. Assuming the cost per study to be +250, the cost of the study was +3945 per alteration of diagnosis and +6482 per alteration of treatment.