Cell transplantation to the brain and spinal cord is awell-established research tool for studies on cellular andmolecular mechanisms, but can it be developed into a usefultherapuetic approach in human neurological disorders?Clinical trials in patients with Parkinson's disease haveprovided encouraging evidence, however, no treatment basedon transplantation is available yet. An overview of currentresearch is given in this book. It summarizes the status ofgrafting in humans and discusses scientific problems thathave to be solved before intracerebral transplantation canbecome a useful routine approach to treatment.