Adeno-associated virus vectors (type2) containing the marker gene--green fluorescent protein (AAV2-GFP) were used to transduce subventricular zone neural stem cells (NSCs). NSCs labelled by gene product--GFP were transplanted into adult Sprague-Dawley rat striatum. The animals were allowed to survive for 45 days, 90 days and 120 days before they were perfused. All the fixed brains were serially sectioned in the saggital plane,at the sickness of 30 microm with a cryostat microtome. These results showed that, at all stages, GFP labelled NSCs were seen in the injection sites,and a lot of them dispersed in the host brains. GFP labelled NSCs showed directional migration 45 days following transplantation. 120 days after transplantation, a group of GFP labelled NSCs migrated dorsally and posteriorly, reached corpus callosum; another group of transplanted NSCs migrated ventrally and posteriorly,reached substantia nigra, moreover,a number of these cells migrated through or over the substantia nigra and reached the more ventral boundary of the substantia nigra. The migrating NSCs were in chains, GFP labelled cells in substantia nigra were beta-tubulin III immunoreactive.