Background and Purpose—Reversible cerebral vasoconstriction syndrome (RCVS), characterized by severe headaches and reversible constriction of cerebral arteries, may be associated with ischemic and hemorrhagic strokes. The aim of this study was to describe the frequency, patterns, and risk factors of intracranial hemorrhages in RCVS. Methods—We analyzed prospective data on 89 consecutive patients with RCVS, of which 8 were postpartum and 46 used vasoactive substances. Standard bivariate and multivariate statistical tests were applied to compare patients with and without hemorrhage. Results—Thirty patients (34%), of which 5 were postpartum and 12 used vasoactive substances, developed at least 1 type of intracranial hemorrhage, including cortical subarachnoid (n=27), intracerebral (n=11), and subdural hemorrhage (n=2). Patients with hemorrhage had an older age (46.6 versus 41.6 years, P=0.049) and were more frequently females (90% versus 51%, P=0.0017) or were migrainers (43% versus 19%, P=0.022) than those ...