Temperament (Mizaj), as an individual factor, has great importance in traditional medicine and its use in diagnosis and treatment of diseases, as well as the individual lifestyle is very common. Since medicine moves toward Personalized Medicine, the root of individual differences will find its position in different aspects of medicine in early future. In traditional medicine, temperament is defined as the only cause of individual differences and this scientific principle in the near future will be highly regarded. Recent studies also indicate the important role of temperament in body functions. Association of temperament with autonomic and immune systems, blood groups and various diseases also confirms this role. The present study provides a scheme of the history of temperament science, current status and its future, and tries to map a correct portray of temperament trend from the past to the future.