Icariin is the major active constituent of Epimedii Herba. Our recent study showed that icariin displayed anti-inflammatory potential. One novel derivate of icariin is 3,5,7-Trihydroxy-4''-methoxy-8-(3-hydroxy-3-methylbutyl)-flavone (ICT). Little is known about ICT''s pharmacological activities. In our study, the anti-inflammatory properties of ICT were evaluated. Murine RAW264.7 cells and C57BL/6J mice stimulated by lipopolysaccharide (LPS) was used as in vitro and in vivo inflammatory model, respectively. Our data showed that ICT (1--100 mu mu g/mL) significantly inhibited LPS-induced tumor necrosis factor-alpha alpha (TNF-alpha alpha), nitric oxide (NO), prostaglandin E2 (PGE2) production in vitro. These effects did not depend on cytotoxicity. The in vivo assay displayed that pretreatment of C57BL/6J mice with ICT (25--100 mg/kg, by gavage) for 3 days decreased LPS-induced serum levels of TNF-alpha alpha, PGE2, and neutrophils CD11b expression dose-dependently. Furthermore, our data suggested that ICT reduced NO and PGE2 levels by inhibiting inducible NO synthase and cyclooxygenase-2 protein expression. To our knowledge, it is the first time that the anti-inflammatory effects of ICT have been evaluated.