Tibetan medicated-bath therapy has been applied to patients with rheumatoid arthritis for centuries. However, the detailed action mechanism of Tibetan medicated-bath therapy on the morphology and function of joints remains unknown. We designed our investigation to evaluate the efficacy of Tibetan medicated-bath therapy on adjuvant arthritis (AA) of rats in comparison with water-bath and dexamethasone administration. AA was induced by intradermal injection of Mycobacterium butyricum suspended in sterile mineral oil. The control animals were similarly injected with sterile vehicle. Eight days after injection, rats were treated with fresh-water bath, Tibetan medicated-bath (40°C, 15 min) or intramuscular injection with dexamethasone for 21 consecutive days after which we evaluated the severity of arthritis visually and microscopically and measured serum interleukin (IL)-6 and tumor necrosis factor (TNF)-α levels. While arthritis did not significantly change after water-bath treatment, the Tibetan medicated-bath and dexamethasone groups showed diminished joint swelling and alleviation of, inflammatory cell infiltration and the destruction of bone and cartilage. Serum IL-6 and TNF-α levels significantly decreased. Our results demonstrated that Tibetan medicated-bath therapy exerted a reliable effect on rat adjuvant arthritis, which may be involved in the inflammatory cytokines, IL-6 and TNF-α. Our data provide evidence for clinical use of Tibetan-medicated bath therapy for arthritis patients.