Panax ginseng C. A. Meyer (Araliaceae) is listed in Shen Nung Pentsao Ching(神農本草經) as the remedy for replenishing the primodial qi(氣), restoring pulse, treating collapse, tonifing the spleen and lag, promoting the production of body fluid to quench thirst, tranquilizing the mind, and improving the function of brain. The prescriptions of In Sam Tang(人參揚) are also recorded in many other Chinese medical books. The identification of the age of Panax ginseng is very important in commercial market as well as in research field. However, any reports about it have not been clearly established yet. To clarify the criterion, the morphological and anatomical characteristics of the roots of various age Panax ginseng cultivated in Korea were studied. The characteristics of cork layer, secretory canal, and vessel were shown to bε useful keys to confirm the age of Panax ginseng.