Genistein 0.5 and 2% effectively attenuated the cytokine level and mRNA expression in IMQ-induced mouse skin, including IL-1β, IL-6, TNF-α, IL-17 and IL-23. Also, genistein significantly suppressed chemokine CCL2 mRNA level and cytokine MCP1 level in psoriasis-like lesions. Genistein was proved to have a superior inhibition effect than the positive control, Daivonex (calcipotriol ointment). The gene discussed is IL17A; the disease is psoriasis.