To investigate the efficacy in treating erectile dysfunction and to develop a natural drug without complications, the results of ginseng treatments are compared to placebo and other drug. A total of 90 patients with 30 patients in each group were closely followed. Changes in symptoms such as frequency of intercourse, premature ejaculation, and morning erections after treatment were not changed in all three groups (p > 0.05). However in the group receiving ginseng, changes in early detumescence and erectile parameters such as penile rigidity and girth, libido and patient satisfactions were significantly higher than that of other groups (p < 0.05). The overall therapeutic efficacies on erectile dysfunction were 60% for ginseng group and 30% for placebo and trazodone treated groups, statistically confirming the effect of ginseng (p < 0.05). No complete remission of erectile dysfunction was noted, but partial responses were reported. No cases of aggravation of symptoms were reported. AVS-penogram, which is a recording of penile hemodynamic changes during the natural erection after audiovisual erotic stimulation, is not changed after administration of ginseng. However if administered for a prolonged period of time, the cummulative effect on vascular flow might be seen. The administration of Korean red ginseng has shown to have superior effects compared to the placebo or trazodone. Definitely more researches are required to elucidate the mechanism of ginseng. The effects of saponin, extracted from ginseng, on smooth muscle of erectile tissues, can be evaluated using organ chamber or nitric oxide titration, thereby pinpointing the exact action mechanism of saponin. As more informations are available, possible breakthrough in treatment of erectile dysfunction could be arisen from active saponin extracted from red ginseng, bringing hopes to many sufferers of erectile dysfunction.