This chapter reviews the clinical observations following neural transplantation in three major brain disorders, namely Parkinson's disease (PD), Huntington's disease (HD), and stroke. It discusses the scientific advancements that are needed for the further development of cell-based therapies. The clinical trials with embryonic mesencephalic grafts in PD patients have provided proof-of-principle that cell replacement can restore function in the parkinsonian brain. Cell-based approaches give rise to long-lasting, major improvements of mobility and suppression of dyskinesias without the need for further therapeutic interventions. The optimum strategy for neuronal replacement in stroke will probably be to combine transplantation of neural stem cells (NSCs) close to the damaged area with stimulation of neurogenesis from endogenous NSCs. Recent progress shows that specific types of neurons and glia cells suitable for transplantation can be generated from stem cells in culture.