Gastroesophageal reflux disease (GERD) is a very common disorder that affects substantially the patient's quality of life. A number of important new developments in the diagnosis, clinical management, and medical, endoscopic, and surgical therapies were described in 2003, and they are summarized here.Most patients with symptomatic GERD do not have erosive reflux disease. Transient lower esophageal sphincter relaxations and hiatal hernias have emerged as major and interacting factors in GERD. Stretch receptors in the fundus are more relevant than tension receptors in triggering transient lower esophageal sphincter relaxations and subsequent reflux. The wireless Medtronic Bravo pH system has been validated as an alternative to conventional pH monitoring and has better tolerability. The mainstay of medical therapy for GERD is the use of proton pump inhibitors, with as yet no superiority of any one agent over all others. Several endoscopic antireflux therapies aiming at creating an antireflux barrier and reducing or eliminating the need for chronic medical therapy or fundoplication have been introduced and validated as feasible, safe, and effective. It may be possible now to stratify patients with GERD to treatment with either endoscopic therapy or surgery according to the size of hiatal hernia, lower esophageal sphincter pressure, Barrett esophagus, and significant pulmonary symptoms.Key developments in the recognition and management of GERD in 2003 will have significant implications for clinical practice or research.