Objectives : This study evaluates the hair growth promoting effect of Yonnyuniksoogobon-dan on shaved C57BL6 mice. Methods : Yonnyuniksoogobon-dan was administered orally (Group I) and both orally and by skin application (Group II) once a day for 12 days. The experimental groups were compared to Control, which was orally administered physiological saline solution. Hair regrowth was photographically and histologically determined during the experimental period. The levels of hair growth cycle related factors (EGF, TGF-${eta}$1) and vascular factors (VEGF, iNOS) were also determined by immunohistochemistry. On gross observation of hair growth, both Group I and Group II shaved C57BL6 mice showed accelerated hair regrowth. Results : The hair regrowth index of Group I increased significantly from 7 days (P<0.05) to 12 days (P<0.01) after shaving and that of Group II was significantly higher at 12 days (P<0.05). On histological observation, both Group I and Group II demonstrated histological improvement and increases in the number and diameter of the hair follicles. EGF expression on the root sheath of hair follicles was up-regulated in both Group I and II. TGF-${eta}$1 expression on the root sheath of hair follicles was unchanged in both Group I and II. VEGF expression in the tissues surrounding hair follicles was up-regulated in both groups. iNOS expression in the tissues surrounding hair follicles was down-regulated in both groups. Conclusions : These results suggest that Yonnyuniksoogobon-dan promotes hair growth and this effect is related to up-regulation of EGF and VEFG expression and down-regulation of TGF-${eta}$1 and iNOS expression on hair roots