Rumination syndrome is a functional gastrointestinal disorder characterized by effortless postprandial regurgitation. The disorder appears uncommon, although only limited epidemiologic data are available. Awareness of the characteristic symptoms is essential for recognizing the disorder, and thus avoiding the long delay in diagnosis, that many patients experience. Although objective testing by postprandial esophageal high-resolution impedance manometry is available in select referral centers, a clinical diagnosis can be made in most patients. The main therapy for rumination syndrome is behavioral modification with postprandial diaphragmatic breathing. This clinical practice update reviews the pathophysiology, diagnosis, and treatment of rumination syndrome. Best Practice Advice 1: Clinicians strongly should consider rumination syndrome in patients who report consistent postprandial regurgitation. Such patients often are labeled as having refractory gastroesophageal reflux or vomiting. Best Practice Advice 2: Presence of nocturnal regurgitation, dysphagia, nausea, or symptoms occurring in the absence of meals does not exclude rumination syndrome, but makes the presence of it less likely. Best Practice Advice 3: Clinicians should diagnose rumination syndrome primarily on the basis of Rome IV criteria after an appropriate medical work-up. Best Practice Advice 4: Diaphragmatic breathing with or without biofeedback is the first-line therapy in all cases of rumination syndrome. Best Practice Advice 5: Instructions for effective diaphragmatic breathing can be given by speech therapists, psychologists, gastroenterologists, and other health practitioners familiar with the technique. Best Practice Advice 6: Objective testing for rumination syndrome with postprandial high-resolution esophageal impedance manometry can be used to support the diagnosis, but expertise and lack of standardized protocols are current limitations. Best Practice Advice 7: Baclofen, at a dose of 10 mg 3 times daily, is a reasonable next step in refractory patients.