In this book, we are going to converge on the most recently effective studies and dynamic researches associated with the use of various strains of stem cells commencing from the embryonic stem cells extended to induced pluripotent stem cells, mesenchymal stem cells and adult stem cells; showing their features, different ways and techniques for preparation, their significant differences and potential uses for treating acute complicated diseases. This brief outlook on the stem cells tend to explain the efficient ways that aroused the differentiation of the stem cells to a whole, healthy working organs from simple hair and teeth to a much more important irreplaceable organ; neurons, eye, liver and lung as an instance. Then we will move to their applications in medical treatments of intractable diseases like Parkinson¿s disease, Coronary artery disease, Osteoarthritis disease, Diabetes mellitus¿ etc.. We covered all these areas with tools, experiments and results obtained from outstanding researches and scientists working or have worked in this field of interest.