Dopaminergic neurons of human origin have many potential research applications such as in vitro studies on biochemical pathways related to neuronal disorders, and potentially direct cell replacement for therapeutic use. Dopaminergic neurons with apparently normal properties can be produced from embryonic stem cells from mice and sub-human primates by the simple procedure of coculturing with the PA6 stromal cell line. Recently, we have demonstrated that this coculture system can induce dopaminergic differentiation in human embryonic stem cells, and the human embryonic stem cell-derived dopaminergic cells exhibit biochemical and functional properties of mature dopaminergic neurons.