Objectives : The purpose of this study is to investigate the effects of Gyejijakyakjimo-Tang on the Allergic Contact Dermatitis caused by 2,4-dinitro-chlorobezene(DNCB). Methods : Twenty eight mice were divided into four groups ; normal, control, experimental group A and B. Control and experimental groups were induced allergic contact dermatitis by DNCB. Experimental group A was orally administered the Gyejijakyakjimo-Tang and experimental group B was orally administered the prednisolone. In this study, ear thickness measurement, auricle microphotograph observation, MPO(Myeloperoxidase) activity measurement, Reverse transcription-polymerase chain reaction(RT-PCR) analysis of the mRNA level of TNF-$alpha$, IL-$1{eta}$ were performed on these four groups. In addition, the effect of Gyejijakyakjimo-Tang on cell viability and the effect of Gyejijakyakjimo-Tang on the compound 48/80-induced histamine release from HMC and RPMC were measured. Results: 1. Both experimental group A and B had decreased ear thickness compared with control group In contact hypersensitivity assay. 2. In experimental group A, inflammatory edema was similarly observed comparing to control group. Nevertheless, inflammatory edema was obviously reduced in experimental group B. In both experimental group A and B, pathological lesion of dermatitis were alleviated. In addition, the numbers of infiltrated inflammatory cells were decreased compared with control group. 3. Compared to the normal group, there was a noticeable increase in MPO activity in control group. However, in experimental group A and B, it showed remarkable inhibition of the increase in MPO activity comparing with control group. 4. The level of expression of TNF-$alpha$, IL-$1{eta}$ in experimental group A and B were meaningfully lower than those in control group. 5. In MTT assay, the concentrations of Gyejijakyakjimo-Tang that were used on the test had no cytotoxicity. 6. Gyejijakyakjimo-Tang dose-dependently inhibited the compound 48/80-induced histamine release from both HMC and RPMC. Conclusions : According to above experiments, Gyejijakyakjimo-Tang was effective on allergic contact dermatitis.