The present study was designed to elucidate the physiological changes with age by chronic administration of red ginseng. All rats were reared in the conventional system. Ginseng treated rats were continously supplied with ginseng water extracts together water from 6 weeks of age to the age 24 months. Rats did not show any discernible signs or the rejection symptoms by red ginseng water extracts. A long-term administration of red ginseng extracts did not cause any physiological changes in the gain of body and organs weight, food intake and general properties of urine. However, red ginseng caused to decrease the level of serum cholesterol, glucose and TBARS, and it attenuated effectively the age-dependent decline of LDH activity. Other biochemical parameters measured from blood and general properties of urine were not significantly changed. These results suggest that long-term administration of red ginseng to rat does not cause any clear physiological changes in appearance and urine, and it retards age-related deteriorations in some biochemical parameters such as LDL-cholesterol, glucose and LDH in serum.