Thromboembolism is a complication of hematopoietic stem cell transplant. However, a literature search showed no previous reports of cerebral infarction during the thrombocytopenic stage after hematopoietic stem cell transplant. A 35-year-old woman with acute lymphoblastic leukemia (precursor B-cell type) was treated with hematopoietic stem cell transplant after induction and consolidation chemotherapy. On day 2 after transplant, she was unconscious, and had urinary incontinence and left hemiplegia. A computed tomography scan of the brain showed an acute ischemic infarct in the right middle cerebral artery region and an old infarct at the left thalamus without atherosclerosis. Factor VIII level was elevated (190%; normal range, 60% to 150%). She was treated with rehabilitation and low-dose aspirin. At 6 months after transplant, the leukemia remained in remission and she had no further thromboembolic events. This case suggests that prudent treatment of patients who have hematopoietic stem cell transplant may include monitoring for thromboembolism and testing factor VIII level before transplant.