Background and Objectives : There are many diagnostic modalities to evaluate laryngopharyngeal reflux. However, ideal diagnostic methods have not been established yet. The purpose of this study is to evaluate the effectiveness of Water-Siphon test as a diagnostic test of laryngopharyngeal reflux. Subjects and Methods : From November 2006 to September 2007, we performed esophagography with Water-Siphon test and questionnaire, physical examination for 227 patients with laryngopharyngeal reflux symptoms. The results of Water-Siphon test were classified according to the degree of reflux, the number of reflux, the retention time and analyzed about the relationship with the reflux symptom index (RSI), reflux finding score (RFS). Results : The degree of reflux was related with pseudosulcus, thick endolaryngeal mucus. The number of reflux was related with thick endolaryngeal mucus. A positive predictive value of Water-Siphon test was 82.7% and sensitivity was 91.5%. Conclusion : Water-Siphon test is a reliable diagnostic test for laryngopharyngeal reflux.