Objective : To study the effect of the Insamyangyoung-tang(ISYT) extract on the skin barrier function, the skin pH, skin humidity and transepidermal water loss(TEWL) were measured and histological changes were observed in DNCB(2,4-dinitrochloro-benzen)-induced contact dermatitis(CD) hairless mice. Methods : The male hairless mice were divided into three groups. Each group consisted of 15 mice. The normal group which had acetone- olive oil applied. The control group which had intentionally induced CD by DNCB and it was fed normal saline orally. The ISYT group which had intentionally induced CD by DNCB and it was fed ISYT extract orally for 7 days. The three groups were checked 24h, 48h and 72h later after inducing CD, and the skin pH, skin humidity and TEWL were observed. Tissue samples were taken, and damage to the epithelial cell was observed. Statistical analysis was performed by using one way-ANOVA: significance was set at p values less than 5% (p<0.05). Results : ISYTextract efficiently maintained the pH balance, it kept the skin humidity at a normal level, and it inhibited TEWL of the DNCB-induced CD hairless mouse. The damage to the epithelium was decreased and the regeneration power of the skin was increased in the ISYT group. Conclusion : Insamyangyoung-tang has a good effect on the skin barrier function of DNCB induced contact dermatitis hairless mice.