Objective: To expound the mechanism of traditional Chinese medicinal herbs bath for treatmenf of rheumatoid arthritis from the angle of microcirculation. Methods: Observations were made on nailfold microcirculation in 130 patients with rheumatoid arthritis before and after traditional Chinese medicinal herbs bath. Results: Traditional Chinese medicinal herbs bath could obviously improve disorders of microcirculation (P0.01), increase blood flow velocity (P0.01) and eliminate the aggregation of erythocytes (P0.01).