In Traditional Chinese Medicine (TCM), the functions of the brain are dispersed to five zang organs, and are maintained by comprehensive functional interactions among the five zang organs. Therefore, brain diseases are regarded as systematic diseases in TCM, and their treatments are aimed to normalize not only the activity of the organs, but also the balance of functional interaction. In addition, interestingly, the functional interaction between the five zang organs in TCM resembles a biological model based on chaos theory. These features of TCM derive from its theoretical basis in Yin-Yang and the five elements. In conclusion, TCM had co-opted the basic idea of a complex system for the diagnosis and treatment of human diseases thousands years ago. Research into TCM should not only evaluate the effects of herbal medicine or acupuncture, but should take into consideration the view of human beings in TCM.