Objective: To investigate the effects of baicalin on expression of inducible nitric oxide syn-thase (iNOS) in fibroblasts and its mechanisms in treating psoriasis. Methods: Fibroblasts cultured in vitro were stimulated with tumor necrosis factor-α (TNF-α), interferon-γ(IFN-γ), interleukin-8 (IL-8) in different groups. iNOS was detected by western blot and immunocytochemistry assay, and in addition, the effects of baicalin on its expression were investigated. Results: Fibroblasts did not express iNOS without cytokine stimulation. When treated for 24 h with 1.0×106 U/LTNF-α, 0.2×106U/L IFN-γ, 0.2×106 pg/L IL-8 alone or in combinations indicated, fibroblasts produced iNOS when stimulated by TNF-α alone while neither IFN-γ nor IL-8 could induce the production of iNOS. The combination of TNF-α and IL-8 induced a strong expression of iNOS, the combined exposure of three kinds of cytokines showed an even stronger effects. The strongly stained area was in the cytoplasm near the nuclei. Expression of Objective: To investigate the effects of baicalin on expression of inducible nitric oxide syn-thase (iNOS) in fibroblasts and its mechanisms in treating psoriasis. Methods: Fibroblasts cultured in vitro was stimulated with tumor necrosis factor-α (TNF-α), interferon -γ(IFN-γ), interleukin-8 (IL-8) in different groups. iNOS was detected by western blot and immunocytochemistry assay, and in addition, the effects of baicalin on its expression were investigated. Results: Fibroblasts did not express iNOS without cytokine stimulation. When treated for 24 h with 1.0×106 U/LTNF-α, 0.2×106 U/L IFN-γ, 0.2×106 pg/L IL-8 alone or in stations indicated, fibroblasts produced iNOS when stimulated by TNF-α alone while neither neither IFN-γ nor IL-8 could induce the production of iNOS. The combination of TNF-α and IL-8 induced a strong expression of iNOS, the combined exposure of three kinds of cytokines showed an even than effects The strong stained area was in the cytoplasm near the nuc Lei. Expression of