Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. The most classic symptom is a sudden-onset (thunderclap) headache along with neck stiffness, vomiting, a decreased level of consciousness, and seizure. As with any stroke, focal neurologic deficits are commonly present, and rapid neurologic deterioration may ensue without prompt diagnosis and intervention. An SAH should be suspected in any person presenting with thunderclap headache and neurologic symptoms, and the diagnosis can be confirmed with neuroimaging or lumbar puncture (LP). Treatment consists of reversal of anticoagulation, control of blood pressure, and neurosurgical intervention to contain the bleed and/or relieve elevated intracranial pressure (ICP). Even with prompt neurosurgical intervention, SAH carries a high mortality rate.