In recent years, considerable new information has become available on the pathogenesis, diagnosis and therapy of gastroesophageal reflux. Gastric contents, mucosal resistance, esophageal acid clearance, and gastric emptying are now recognized, along with incompetency of the lower esophageal sphincter, as contributing factors to gastroesophageal reflux disease. The potential tests for reflux are reviewed and the diagnostic accuracy of each is evaluated. A diagnostic approach to the patient with reflux symptoms is outlined that considers the sensitivity and specificity of these various tests as well as their availability to the generalist and gastrointestinal specialist. Finally, an overview of the current therapy for reflux disease summarizes the controlled studies in the medical literature.