One can study the Islamic medicine within two stages: establishment; compiling and innovation. In the establishment stage the Islamic medicine was created on the basis of Greek rules especially Galenic medicine, but it was not limited to the Greek Galenic models. In this stage it freed itself from the fame of Galen through expansion of dialogues and scientific discussions and adding new elements to the science of medicine; writing on the subjects not dealt with by Galen; criticizing Galen and using non-Greek models such as Indian ones. The compiling and innovation stage continued for at least five centuries (early fourth century (H) to the middle of the ninth century/centuries 10-15); and it can be considered as the Islamic medicine era in the general history of medicine. In this stage the most important differences in the field of general principles were: separation of medicine and philosophy; dominance of the medicine’s scientific section in comparison with its theoretical one; surpassing mere logical reasoning by experience and experiment; and the priority of scientific clinical observations to analogical theories. Therefore, Islamic medicine separated from philosophy and only dealt with medical subjects and physicians started to expand medical branches and specializing them via writing and practicing. Moreover, it enabled them to correct predecessors’ mistakes and add many new subjects.