Gamipaidok-san(GPDS) is the Hyungbangpaidok-san prescription fortified with the additional ingredients known to be effective for dermatitis. So it has been used for atopic dermatitis in the clinic work actually. In this study, we investigated the effects of GPDS on in vitro and in vivo anti-allergic effect on RBL-2H3 rat basophilic leukemia Cells and on IgE-induced passive cutaneous anaphylaxis (PCA) in mice. The in vitro anti-inflammatory activity of GPDS in RAW 264.7 cells was investigated. GPDS potently inhibited $eta$-hexosaminidase release from RBL-2H3 and the IgE-mediated PCA reaction in mice. GPDS inhibited LPS-induced NO and PGE2 production in a dose-dependent manner Furthermore, It also inhibited inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expression in RAW 264.7 cells, and the activation of the transcription factor, NF-kB, in nuclear fraction. The antiallergic action of GPDS may originate from anti-inflammatory activities, and can improve the inflammation caused by allergies.