Several biochemical parameters related to aging were evaluated after a hot-water extract prepared from unossified pilose antler of Cervus nippon TEMMINCK var. mantchuricus Swinhoe (Rokujo) had been administered orally for 8 successive days to senescence-accelerated mice (SAM), a novel murine model of spontaneously promoted aging. It was found that the repeated oral administration of Rokujo had significant restoring effects on the physiological degenerations which were associated with the development of senile symptoms. These effects included (1) an increase in the plasma testosterone level in male mice; (2) a decrease in the contents of malondialdehyde in the liver and brain; (3) an increase in the liver protein contents; (4) an increase in the liver superoxide dismutase activity; and (5) a decrease in the activity of monoamine oxidase B in the liver and brain membranes. Most of these effects were selectively observed in the senile-prone strain of SAM (SAM-P) as compared to the normal, resistant strain (SAM-R). The present data suggest that Rokujo may exert an anti-aging action in male senile animals.