The rumination syndrome is a behavioral condition characterized by postprandial regurgitation. In contrast to what many think, the disorder does not exclusively occur in mentally disabled patients or children but also in otherwise healthy adults. As symptoms of postprandial regurgitation are often mistaken for gastroesophageal reflux disease or vomiting, the rumination syndrome is an underappreciated condition. Rumination episodes are caused by an intragastric pressure increases which forces the gastric content into the esophagus and mouth and occurs during 3 distinct mechanisms: primary rumination, secondary rumination, and supragastric belch-associated rumination. Combined manometry-impedance can distinguish rumination from gastroesophageal reflux disease. Treatment of the rumination syndrome consists of a thorough explanation of the mechanisms underlying the rumination episodes and behavioral therapy. As behavioral therapy is a time-consuming and often expensive treatment, we propose that a clinical suspicion of the disorder is always confirmed by a manometry-impedance measurement.