Subarachnoid hemorrhage (SAH) is defined as the presence of blood in the subarachnoid space and cisterns of the base. The source is variable and may be due to rupture of intracranial aneurysms (80%), arteriovenous malformations (AVMs), tumors and trauma cranoencefálicos. The HSA is a relatively common disease with an incidence is 5% of cerebral vascular disease. The estimated prevalence of 10 new cases per 100,000 people each year. The proportion of HSA varies with age, being the most prevalent group between 50 and 60. It is a pathology with high morbidity and mortality, since a high percentage of patients (10-15%) did not reach the hospital and the remaining group of about 15% die. Angiography is the standard diagnostic procedure, although angiography is an important alternative. Treatment should be administered as soon as possible within 72 hours, both surgical and endovascular techniques to prevent complications such as rebleeding, vasospasm and hydrocephalus, being the most widely used surgical approach is the pterional craniotomy. The prognosis depends on careful handling and the degree of the initial hemorrhage.

          Key words:  Subarachnoid hemorrhage, Intracraneal aneurysm, Craniotomy.