We spend a quarter of every night on the dream, it means for us to spend about six years having a dream. But, any portion of the dream are remained the mystery in these days and it goes without saying that these mystery have not been solved from old times. So. the people have not known about the essences of dream for a long time although they have experienced in dreaming in the early days of human history. But, It is necessary to consider the dream to modality of disease diagnosis because many evidences that the dream represents the physiologic and pathologic changes in the human have been proved in recent days. So, we are going to inquire into the things being scattered over many texts of the Oriental Medicine, including the Internal Classics(內經). about the dream and to look the diagnostic significances of the dream with some examples of the modern psychiatric accomplishments.