The expansion of human neural stem cells in vitro might overcome the poor donor supply of human fetal neural tissue in transplantation for Parkinson's disease. However, the differentiation of human neural stem cells into dopaminergic neurons has proven difficult. In the present study, we investigated the effects of cytokines, trophic factors of developmental striatum and Ginkgolide on differentiation of human neural stem cells (hNSCs) into TH-ir neurons. The immunoreactivity to tyrosine hydroxylase (TH), a distinctive marker for dopamine neurons was used to assess dopaminergic neuronal phenotype. We demonstrate that human neural stem cells expanded in vitro can efficiently differentiate into TH-ir neurons by induction. These stem cells might serve as a continuous, on-demand source of cells for therapeutic transplantation in patients with Parkinson's disease.