We experienced a case of acute cerebral infarction during spinal anesthesia. The patient was a seventy years old male with diagnosis of right femur periprosthetic fracture scheduled for a open reduction & internal fixation under spinal anesthesia. Intraoperatively, he developed a mental confusion and his blood pressure decreased from 115/70 mmHg to 80/45 mmHg. After operation, he appeared to have left hemiparesis and left facial palsy. Angiogram revealed thrombus in superior division of the right middle cerebral artery. He expired 3 months after the surgery despite supportive measures.