CONTEXT: Intracranial hemorrhage must be excluded prior to administration of thrombolytic agents in acute stroke. OBJECTIVE: To evaluate physician accuracy in cranial computed tomography scan interpretation for determining eligibility for thrombolytic therapy in acute stroke. DESIGN: Administration of randomly selected, randomly ordered series of 15 computed tomography scans from a pool of 54 scans that demonstrated intracerebral hemorrhage, acute infarction, intracerebral calcifications (impostor for hemorrhage), old cerebral infarction (impostor for acute infarction), and normal findings. PARTICIPANTS: A convenience sample of 38 emergency physicians, 29 neurologists, and 36 general radiologists. MAIN OUTCOME MEASURES: Physician determination of eligibility for thrombolytic therapy based on computed tomography scan interpretation. RESULTS: Average correct score by all physicians on all computed tomography scans was 77% (95% confidence interval, 74%-80%). Of 569 computed tomography readings by emergency physicians, 67% were correct; of 435 readings by neurologists, 83% were correct; and of 540 readings by radiologists, 83% were correct. Overall sensitivity for detecting hemorrhage was 82% (95% confidence interval, 78%-85%); 17% of emergency physicians, 40% of neurologists, and 52% of radiologists achieved 100% sensitivity for identification of hemorrhage. CONCLUSION: Physicians in this study did not uniformly achieve a level of sensitivity for identification of intracerebral hemorrhage sufficient to permit safe selection of candidates for thrombolytic therapy.