Cannabinoid hyperemesis is a syndrome characterized by severe nausea and hyperemesis associated with chronic marijuana abuse and marked by compulsive bathing habits, which temporarily alleviate symptoms. We describe the syndrome in 4 adult patients for whom extensive gastrointestinal evaluations failed to identify another clear cause. Cessation of marijuana use resulted in the alleviation of their symptoms. Because recreational and medical use of marijuana is increasing in the United States, this condition should be considered in many patients who present with cyclical vomiting.