Objective To explore the survival,migration and differentiation of embryonic stem cells after transplantation into striatum and provide advantageous data for feasibility and safety of therapeutic transplantation. Methods We transplanted embryonic stem cells(undifferentiated ESCs and ESCs that had already developed into the stage of neural progenitor cells respectively) into striatum of the rat.Then differentiated cells were determined by morphological observation,Nissl's staining,TH and BrdU immunocytochemistry. Results We found that after transplanted 4 weeks,partially differentiated ESCs could survive and migrate into the surrounding host tissue.Some of them differentiated into TH-positive cells which had Nissl's bodies in cytoplasm.Whereas undifferentiated ESCs couldn't differentiate into TH-positive cells effectively and have the tendency to form tumor.Conclusion When conducting transplantation experiments of ESCs,it's better for ESCs to be induced into the stage of neural progenitor cells first and then transplanted.;