Rumination is a syndrome characterized by repetitive regurgitation of small amounts of food from the stomach. The food is then partially or completely rechewed, reswallowed, or expelled. This syndrome is relatively common in infants and mentally challenged persons, but it also occurs in adults with normal intelligence. The rumination syndrome is an underappreciated condition in adults who frequently receive a misdiagnosis of vomiting due to gastroparesis or gastroesophageal reflux. Difficulties in establishing the correct diagnosis may be caused by a lack of awareness of the condition among physicians. This syndrome must be considered in the differential diagnosis of a patient with regurgitation, vomiting (especially postprandial), and weight loss. Reassurance, explanations, and behavioral therapy are currently the mainstays of treatment in adults with normal intelligence who have the rumination syndrome. Appropriately controlled trials are needed to establish the best therapy.