Background: Cannabis is one of the most commonly used drugs worldwide with several side effects. Although it is used also as an antiemetic and appetite stimulating drug, it may have a paradoxal effect. Cannabinoid hyperemesis syndrome is a clinical syndrome characterized by repeated vomiting and abdominal pain associated with chronic cannabis abuse. Case report: We report a case of a 21-year old patient who repeatedly presented at our Department of Internal Medicine with hyperemesis and upper abdominal pain. The diagnostic evaluation showed only mild gastroduodenitis and no obvious causes for patient`s symptoms. During last two presentations he admitted to the chronic abuse of marijuana,which was confirmed with positive findings of tetrahydrocannabinol in urine. Conclusion: In patients with unexplained vomiting and abdominal pain no evidence of organic disease the chronic abuse of cannabis and the cannabinoid hyperemesis syndrome should be considered.