Advances in medicine as a result of stem cell researches could provide cures for many debilitating and degenerative diseases that are characterized by loss of functional cell type such as diabetes, Parkinson’s disease, spinal cord injuries, cerebral palsy, heart diseases, and blindness.During the previous 2 decades, there have been an accumulating strong and convincing experimental evidence from animal studies that stem cells have a potent therapeutic potential. Brain and spinal cord injured mice and rats have been made to walk again. Parkinson's disease in monkey models was relieved. Insulin producing cells have reversed diabetes in animals. The aim of this book is to provide a brief account on stem cell research.