This study investigated the therapeutic e¡ect of neural stem cells transplantedvia the carotid artery atdi¡erent times after intracerebral hemorrhage. A great number of 5-bromo-2-deoxyuridinepositive cells were observed surviving and distributed evenly in the perihematoma areas. Phenotypes of grafted cells depended upon time of transplantation, and the later the cells were transplanted, the larger the percentage of cells that di¡erentiated into neurons. Animals treated at 7 and14 days after injury exhibited the most signi¢cant improvements in behavioral tests. Therefore, intracarotid injection allows e⁄cient delivery of cells to the injured hemisphere, especially during the period 7^14 days after injury, and may potentially be applicable in humans. NeuroReport 18:1019-1023 2007 Lippincott Williams & Wilkins.