The whole plants of Prunella vulgaris (Labiatae) and Thesium chinense (Santalaceae) are used as Hakocho(夏枯草) in the market in Korea. In oriental medicine, these herb drugs are prescribed as a diuretic or antiinflammatory drugs. In order to investigate the efficacy of the plants, the extracts were bioassayed for antiinflammatory action. The water extracts of Prunella Herba and Thesii Herba showed remarkable anti-carrageenin effect and significant inhibition of the swellings in adjuvant arthritis in rats. However, the extracts did not show any inhibition of leucocyte emigration in CMC pouch in rats.