The purpose of this study is to establish and validate the related factors and defining characteristics of flatulence. We established 16 related factors and 13 defining characteristics of flatulence, using expert content validity, diagnostic content validity and factor analysis, Clinical validation was performed on patients from the gastrointestinal section (n=32) and non-gastrointestinal sections (n=22) of two regional hospitals in the north of Taiwan. Cases were enrolled if flatulence lasted for 12 hours or longer. The most common related factors of flatulence are paralytic ileus, bedridden state, and constipation in cases from gastrointestinal section; and bedridden state, constipation, abdominal surgery in cases from Non-gastrointestinal section. The most common defining characteristics of flatulence are tympanic percussion, bloating, and abdominal pain in cases from gastrointestinal sections and tympanic percussion, bloating, abdominal discomfort in cases from non-gastrointestinal sections.