Objective To study the effectiveness of Yuldahansotang against Allergic Contact Dermatitis, the change of cutaneous shape, histochemistry, immunohistochemistry and distribution of apoptotic cells was researched. materials and methods 4-month-old rats were divided into three groups of 10. One is a contrastive group which has applied Acetone olive oil only. Another is ACD group which has intentionally activated Allergic Contact Dermatitis by DNCB. And the other is YST group which has given medication of Yangkyuksanhawtang extract. Each group of mice were observed after 24, 48 and 72 hours. results 1. With the result of Contact hypersensitivity assay, YST group shows appreciably less ear swelling than ACD group. 2. Comparing YST and ACD groups to each other regarding general change of skin, YST group shows less hyperplasia of epidermis, less migration of inflammatory cells and less damage of epidermis than ACD group. 3. Regarding the change of collagen fiber, ACD group has appeared to be low in number of collagen fiber while YST shows similarity with the contrastive group. 4. In dermis YST group has showed lower number of mastocyte than ACD group and is granulated type. 5. In dermis YST group has showed less MAC-1,IL-1, $IL-2R-{alpha}$, ICAM-1 and VCAM-1 than ACD group. 6. The distribution of apoptotic cells has appeared littler in YST group than in ACD 7. Among signal molecule of apoptosis Bcl-2 has distributed more in YST group than ACD group and Bax and Fas has distributed less in YST group than ACD group.