Cerebrovascular disorders contribute to the morbidity and disability associated with illicit drug use. Drug abusers have an increased risk of both hemorrhagic and ischemic stroke. In geographic areas with a high prevalence of illicit drug use, drug abuse is a frequent cause of stroke in the young adult. The illicit drugs more commonly associated with stroke are psychomotor stimulants, such as amphetamine and cocaine. Less commonly implicated are opioids and psychotomimetic drugs, including cannabis. Toxicology screening for illicit drugs should be done in young patients with stroke with no obvious cause, or if suggested by history or examination. Although in some patients the mechanism of stroke is identified using neuroimaging and other modern diagnostic tools, in a sizeable fraction of cases the mechanism of stroke remains unclear. Further studies are needed to elucidate the role of hemodynamic and immunologic mechanisms in these cases.