OBJECTIVE: To summarize the current knowledge of the mechanisms leading to rebleeding and the prevention of rebleeding after subarachnoid hemorrhage (SAH). METHODS: A literature search was performed to investigate factors associated with rebleeding after SAH. RESULTS: The review of the literature revealed that rebleeding is a complex and multifactorial event involving hemostasis, pathophysiologic, and anatomic factors. Administration of antifibrinolytics has been shown to have a dramatic effect on the rebleeding rate, so changes in coagulation and fibrinolysis must be involved in rebleeding. CONCLUSIONS: Further studies are warranted before the exact mechanisms leading to rebleeding are established and the optimal preventive measures are made available. At the present time, antifibrinolytic therapy remains the only realistic protective measure during the initial 6 hours after SAH during which the rebleeding rate is highest.