Objectives The purpose of this study is to investigate the effects of Sesamum indicum extracted (SEI) on atopic dermatitis in an in-vitro and in-vivo experiment using a MC/9 murine mast cells and a NC/Nga mouse. Methods In-vitro experiment, IL-4, IL-5, IL-6, IL-13, TNF-${\alpha}$ and GM-CSF mRNA expression were evaluated by Real-time PCR, IL-13, MIP-$1{\alpha}$ production by ELISA and manifestations of NFAT-1, NFAT-2, c-jun, c-fos, NF-${\kappa}B$ p65 transcription factors by western blotting. In-vivo experiment, we measured WBC, Eosinophil, Neutrophil, and serum IL-5, IL-13 in NC/Nga atopic dermatitis mouse, IL-5, IL-13, IFN-${\gamma}$, IL-4 in the spleenocyte culture supernatant by ELISA, the absolute cell numbers of CD4+, CD8+, +Gr-1+CD11b, B220+CD23+ in the axillary lymph node (ALN), peripheral blood mononuclear cells (PBMCs) and dorsal skin tissue, IL-5, IL-13 by Real-time PCR, the distribution of tissue inflammation and cellular infiltration by H&E and toluidine blue. Results SEI decreased IL-4, IL-5, IL-6, IL-13, GM-CSF, TNF-${\alpha}$ mRNA expression, IL-13, MIP-$1{\alpha}$ production and the expression of transcription factors including NFAT-1, c-jun, NF-${\kappa}B$ p65 in MC/9 murine mast cells. SEI orally administration decreased cell number of WBC, Eosinophil, the level of serum IgE, total cell number of ALN and dorsal skin tissue, absolute cell number of CD4+, CD8+, B220+CD23+ in the ALN. SEI orally administration also increased absolute cell number of CD8+/CD3+ and decreased Gr-1+/CD11b+ in PBMCs, decreased CD4+ in dorsal skin tissue, inhibited IL-5, IL-13 mRNA expression. Infiltration levels of inflammatory immune cells, mast cells and thickness of epidermis decreased in dorsal skin tissue. Conclusions SEI can regulate allergic inflammatory response suppressed the gene expression and production of cytokines that mediate allergic reactions, and will be able to be effectively utilized in the treatment of atopic dermatitis future.