BACKGROUND: Various health benefits have been attributed to Er-Miao-San (EMS), a traditional Chinese herbal formulation that contains equal amounts of cortex phellodendri (Phellodendron amurense Ruprecht) and rhizoma atractylodis (Atractylodes lancea D.C). However, its effect on the anti-inflammatory activity in human dermal fibroblasts (HDFs) and the mechanism underlying this effect are unknown. RESULTS: This study investigated the effects of EMS on TNF-α-induced MMP-1 expression in HDFs. Our data show that EMS inhibited TNF-α-induced MMP-1 expression in a concentration-dependent manner. Interestingly, EMS maintained IkB content without inhibiting the phosphorylation of MAPKs, which are well-established upstream kinases of NF-kB. Moreover, EMS reduced the level of nuclear p65 protein in HDFs. Luciferase assay revealed that EMS inhibits the transcriptional activity of NF-kBbystabilizing IkB. Our results show that EMS exerts its anti-inflammatory effect by inhibiting NF-kB-regulated genes such as ΙL-1β and IL-8. Moreover, EMS effectively inhibited TNF-α-induced expression of MMP-1 via the NF-kBpathway. CONCLUSIONS: Taken together, our data suggest that EMS could potentially be used as an anti-inflammatory and anti-aging treatment.