"Ham-Hong-Chho" is a folk medicine in Taiwan, derived from the entire plants of Bidens pilosa L. var. minor (Blume) Sherff (Compositae), B. pilosa L. and B. chilensis DC. The anti-inflammatory effect of aqueous extracts of the three plants against paw edema induced by carrageenan and chronic arthritis induced by complete Freund's adjuvant were determined in rats. The results indicated that paw edema induced by carrageenan was significantly decreased by treatment with aqueous extracts (150 or 300 mg/kg) of all three plants (p < 0.05) and that the effect of Bidens pilosa var. minor was the most potent. However, only extracts (500 mg/kg) of B. pilosa L. var. minor and B. pilosa L. significantly decreased the paw edema induced by complete Freund's adjuvant (p < 0.05).