Headache features were compared in 51 patients with acute subarachnoid hemorrhage (SAH), 61 with intraparenchymal hemorrhage (IPH), and 160 with ischemic stroke (IS). SAH patients had more sentinel headaches, more onset headaches, and more bilateral and severe onset headaches than patients with IPH or IS. Vomiting with onset headache was more common in SAH and IPH. In stepwise logistic regression analysis, onset headache and vomiting were direct predictors of SAH, but were inversely related to IS. Sentinel headache was not a predictor of underlying stroke mechanism. The data suggest that some headache features are more frequently associated with particular stroke subtypes and that onset headache and vomiting may be important indicators of stroke mechanism.