AIM To investigate the anti-inflammatory eff ec t of total flavonoids isolated from Platychadus orientalis and its mechanism . METHODS The inflammatory models in mice and swelling of rats hind paws were induced by dimethylbenzene and carrageenan respectivel y. The biosynthesis of leukotriene and ?-glucuronidase release in the cells we re measured by HPLC and fluorescence spectrophotometer respectively. RES ULTS Total flavonoids isolated from Platychadus orientalis remarkably inhibited the ear edema induced by dimethylbenzene in mice at the dose of 12.5 ～50.0 mg?kg -1 and the swelling of rats hind paws induced by carrageenan at the dose of 25.0～50.0 mg?kg -1 . Total flavonoids at final concentrati on of 5.0～125.0 mg?L -1 inhibited 5-HETE and LTB 4 synthesis by 30.5%～ 87.3% and 27.8%～84.3% respectively. In comparision with controls, Total flavono ids at final concentration of 5.0～45.0 mg?L -1 inhibited ?-glucuronidas e release by 13.4%～32.2%. CONCLUSION Total flavonoids isolated f rom Platychadus orientalis has an anti-inflammatory effect which may be rel ated to inhibiting 5-HETE and LTB 4 production and ?-glucuronidase release.