Atopic dermatitis is an allergic inflammatory skin disease caused by aberrant and overreactive immune responses including overactivation of $T_H2$ immune responses, high levels of IgE as well as proinflammatory cytokines and chemokines. We examined whether BHOSB, a traditional herbal medicine, has modulatory effects on various immunological factors related to pathogenesis of atopic dermatitis in ONCB treated NC/Nga mice. Oral administration of BHOSB at the concentration of 10.8 mg/mouse/day significantly inhibited the production of IgE compared with control, and the levels of IgG2a and IgG2b, but not IgG1, were also significantly reduced. Production of IL-6 and TNF-a was greatly decreased. The results from flowcytometry of peripheral blood mononuclear cells indicated that the percentages of C03+C069+ cells and C04+ were significantly decreased by BHOSB. Theses results suggested that BHOSB has suppressive effects on aberrant and overreactive immunological activities in ONCB-induced dermatitis mice of NC/Nga.