Functional dyspepsia (FD) and acid/bile reflux disease are common. These diseases share similar clinical manifestations. Individuals with functional dyspepsia (FD) often present upper abdominal pain or discomfort, bloating, early satiety, loss of appetite, and no organic factors underlie it. Individuals suffering from acid/bile reflux disease often complain heartburn, upper abdominal burning or discomfort. What is more, there are always no specific changes on traditional endoscopy that can be used to differentiate these diseases (except erosive esophagitis). Though proton-pump inhibitor (PPI) test is frequently applied to confirm the diagnosis of acid reflux disease, but certain amounts of individuals with gastroesophageal reflux disease (GERD) do not show favorable response to PPI test. In order to make a distinction of these diseases, esophageal pH-metry is needed, however it is not always available in most clinics. Recent data showed that new endoscopic technology such as Endoscopic Tri-Modal Imaging could demonstrate indistinct lesions caused by GERD which are not detectable by standard endoscopy, subsequently improve endoscopic diagnosis of these diseases. In addition, simultaneous analysis of gastric juice can help to determine whether bile reflux is present or not. As it is known, pathologic refluxes underlie not functional dyspepsia but acid/bile reflux disease. Hence, it is hypothesized that Endoscopic Tri-Modal Imaging in combination with simultaneous analysis of gastric juice could be used to differentiate functional dyspepsia from acid/bile reflux disease.