Objectives Dictamni Radicis Cortex extracts (DRC) has been known to suppress allergic reaction, however the cellular target of DRC and its mode of action remain unclear. The purpose of this study is to investigate the effects of Dictamni Radicis Cortex extracts on DNCB induced atopic dermatitis-like skin lesions of NC/Nga mouse. Methods This study was designed to investigate the effects of DRC extract in the DNP-IgE-induced activation of MC/9 murine mast cell lines in vitro and in the DNCB-induced activation of NC/Nga mouse in vivo. For this investigation, We examined IL-4, IL-5, IL-6, IL-13, TNF-${\alpha}$ and GM-CSF mRNA expression by Real-time PCR, IL-13, MIP-$1{\alpha}$ production by ELISA analysis and manifestations of NFAT1, NFAT2, AP-1 and NF-${\kappa}B$ p65 transcription factors by western blotting in vitro. Then, we examined WBC, eosinophil and neutrophil in NC/Nga mouse, IL-5, IL-13 in serum, IFN-${\gamma}$, IL-4 in the spleenocyte culture supernatant, the absolute cell numbers of $CD4^+$, $CD8^+$, $^+Gr-1^+CD11b$, $B220^+CD23^+$ in the ALN, PBMCs and dorsal skin, IL-5, IL-13 in the dorsal skin by Real-time PCR and the distribution of mast cells by H&E and toluidine blue. Results In vitro the mRNA expression of IL-4, IL-5, IL-6, IL-13, TNF-${\alpha}$, GM-CSF and IL-13, MIP-$1{\alpha}$ production by ELISA analysis were completely abolished by DRC and the western blot analysis decreased the expression of mast cell-specific transcription factors including NFAT-1, NF-${\kappa}B$ p65. In vivo DRC oral adminstration also decreased the counts of WBC, eosinophils and inflammatory cytokines such as IL-13 and IgE in the serum. DRC oral adminstration elevated IL-4 level in the spleenocyte culture supernatant. DRC oral adminstration decreased total ALN cells, total skin cells, cell numbers of $CD4^+$, $B220^+CD23^+$ in the ALN, $^+Gr-1^+CD11b$ in the PBMCs and $CD4^+$, $CD8^+$ in the dorsal skin. The mRNA expression of IL-5, IL-13, thickness of epidermis, inflammation immune cells and mast cells were abolished by DRC in the dorsal skin. Conclusions Histological examination showed that infiltration levels of immune cells in the skin of AD-induced NC/Nga mouse were much improved by DRC oral adminstration. These results, therefore, suggest that DRC can regulate molecular mediators and immune cells that are functionally associated with atopic dermatitis induced in NC/Nga mouse, and may play an important role in recovering AD symptoms.