Objective To observe the meridian tropism of Polygoni Avicularis Herba by tissue distribution of avicularin in rats.Methods Tissue distribution of avicularin in rat following a single iv administration was appointed and observed.HPLC method was established and validated for the determination of avicularin in rat tissues.Results Kidney and bladder were the most important target tissue of avicularin.Conclusion HPLC method is successfully applied to tissues distribution study of avicularin after iv administration to rats,and the results explain Polygoni Avicularis Herba on bladder tropism reasonably.