Gout is a result of metabolic disorders and hyperuricemia is underlying. Lowering elevated plasma uric acid prevents the development of gout, and alloprinol, a xanthine oxidase (XO) inhibitor, is used for that purpose. However, overall incidence of side effects by alloprinol is 5-20%. Thus, development of drugs for the treatment of hyperuricemia with fewer side effects is required. In general, plant medicine has fewer side effects, and there are also plant folk medicines for the treatment of gout. Many of the extracts from traditional medical plants used for the treatment of gout in North America, Vietnam and China possess XO inhibitory activities. Among them there are several extracts from them which showed higher XO inhibitory activity. Extract of Chrysanthemum.sinense in Vietnam folk medicine showed 1/2 potency of alloprinol. Extracts of Chinese folk medicine, Cinnamomum cassia, Chrysanthemum indicum and Lycopus europaeus showed 1/17, 1/21 and 1/25 activities of alloprinol, respectively. Thus, some plant medicines contain chemicals which could be sources for the development of antihyperuricemic agents