A 21-year-old female patient complaining of hemiparesis was diagnosed with right middle cerebral artery infarction. No risk factor was found, despite an extensive young-age stroke work-up, except her history of marijuana use. The patient had smoked marijuana for treating depression for more than five years. Magnetic resonance angiography showed multifocal intra- and extracranial stenoses, suggesting cannabinoid-induced vasculopathy. Since the use of illicit drugs has increased nationwide, physicians should consider it as a possible cause of a stroke due to an unknown etiology.