Abstract: Rat focal cerebral ischemia induced by occlusion and thrombogenesis of middle cerebral artery(MCAO) was used as experimental model to study the effects of extract of Ginkgo biloba(EGb) and the positive control drugs were urokinase and nimodipine on cerebral infarct size and neurological deficits. The results showed that cerebral ischemia and neurological deficits appeared in rat focal cerebral ischemic models, and the degree was of cerebral ischemia larger in occlusion model than in thrombogenesis model. The cerebral infarct size was significantly smaller and neurological deficits greatly improved at large dose of EGb(200 mg·kg^-1, iv), the preventive effect appeared to be better than the treatment effect.The positive control drugs urokinase and nimodipine were also shown to distinctly decrease the cerebral infarct size and inprove the neurological deficits in the models. Small dose of EGb(100 mg·kg^-1, iv) was found to decrease the cerebral infarct size of thrombogenesis model, and improve neurological deficits of both thrombogenesis and occlusion model.EGb was also shown to inhibit the thrombogensis of rat common carotid artery stimulated by electrical current in dosedependent manner. This experiment indicates that EGb might have beneficial effects on prevention and treatment of ischemic stroke and thrombogenesis.