 Many patients with gastro-esophageal reflux disease GERD report that drinking coffee causes heartburn. The purpose of this study is to investigate the effects of coffee on gastro-esophageal acid reflux, and its relation to esophageal motility parameters in patients who are already scheduled to undergo 48 hour wireless pH testing as a result of having symptoms suggestive of GERD. The specific aims are to evaluate the effects of coffee on GERD during daily life and to elucidate the underlying pathogenic mechanism by which coffee induces reflux. 