It has been known for a long time that Palmiwon water extract can be prescribed for the treatment of deficiency of Yang in oriental medicine. But the exact mechanism of it has not been Known yet. In the present experiments, it was attempted to explain the effect of Palmiwon water extract on the serum Hormone level in rabbits and the antifatigue in mice. Palmiwon water extract oral intake showed a increase of serum hormone level in rabbits and the effects of the antifatigue in mice. The results obtained were as follows. 1. The administration of this medicine was observed to cause continuously a significant increase of the testosterone content in the serum from the 7th day to the 21th day. 2. The estradiol centent in the serum, as compared with the control experiment, was seen to increase significantly by the administration of this medicine from the 7th day to the 21th day. 3. The LH and FSH content in the serum, as compared with the control experiment, indicated a tendency toward an increase by the administration of this medicine from the 7th day to the 21 th day, but with no significant difference. 4. In the effect to Palniwon on the antifatigue in mice, swimming time was prolonged in both sample A, B groups than control group, and significance revealed in both sample A, B groups. These data suggest that Palmiwon water extract can increase serum hormone level and that it can have therapeutic effectiveness to the antifatigue.