Gastroesophageal reflux disease (GERD) and irritable bowel syndrome (IBS) are very common disorders in the general population. Symptoms of IBS are commonly encountered in GERD patients, and symptoms of GERD are not uncommon in IBS patients. GERD patients consistently report lower abdominal symptoms, which may be part of the spectrum of GERD symptoms. Alternatively, GERD and IBS may be two distinct manifestations of a similar underlying pathophysiologic process that can affect different levels of the gastrointestinal tract. Although the reason for the overlap observed between GERD and IBS remains to be elucidated, recent studies have demonstrated that GERD patients who also suffer from IBS-like symptoms perceive their GERD-related symptoms as more severe and are less likely to respond to antireflux treatment, as compared with those without IBS.