With widespread treatment of Helicobacter pylori infection, and that peptic ulcer diseases are no longer considered a chronic illness and are declining in most parts of the world, gastroesophageal reflux disease (GERD) predominates the upper gastrointestinal disease spectrum. GERD is a well-defined condition. More innovative research in GERD in recent years led us to new conceptual frameworks on pathogenesis and novel diagnostic tests. The proton pump inhibitor test has evolved to become the diagnostic test of choice for the investigation of patients with the disease spectrum of GERD. Multi-channel intraluminal impedance with pH sensor allows the detection of pH episodes irrespective of their pH values (acid and nonacid reflux). It is useful to measure gastroesophageal reflux in the postprandial period, and in patients with persistent symptoms while on therapy and those with atypical symptoms.