Cerebral infarction (CI) is a crucial complication of aneurysmal subarachnoid hemorrhage (SAH) associated with poor clinical outcome. We aimed at developing an early risk score for CI based on clinical characteristics available at the onset of SAH. Out of a database containing 632 consecutive patients with SAH admitted to our institution from January 2005 to December 2012, computed tomography (CT) scans up to day 42 after ictus were evaluated for CIs. Different parameters from admission up to aneurysm treatment were collected with subsequent construction of a risk score. Seven clinical characteristics were independently associated with CI and included in the Risk score (BEHAVIOR Score, 0 to 11 points): Blood on CT scan according to Fisher grade ≥ 3 (1 point), Elderly patients (age ≥ 55 years, 1 point), Hunt&Hess grade ≥ 4 (1 point), Acute hydrocephalus requiring external liquor drainage (1 point), Vasospasm on initial angiogram (3 points), Intracranial pressure elevation > 20 mm Hg (3 points), and treatment of multiple aneurysms (‘Overtreatment’, 1 point). The BEHAVIOR score showed high diagnostic accuracy with respect to the absolute risk for CI (area under curve = 0.806, P < 0.0001) and prediction of poor clinical outcome at discharge ( P < 0.0001) and after 6 months ( P = 0.0002). Further validation in other SAH cohorts is recommended.