The effects of Ta-383 (0.016, 0.08, 0.4, 2 and 10 mg/kg) and anti-rheumatic drugs (lobenzarit 10 and 50 mg/kg, dexamethasone 0.25 mg/kg) were evaluated on type II collagen-induced arthritis in DBA/1J mice. The arthritis score was markedly suppressed in the groups treated with dexamethasone and TA-383. Serum anti-type II collagen IgG was significantly suppressed in the groups treated with dexamethasone and 0.4 mg/kg TA-383. Histopathological evaluation of the knee joints revealed suppression of the inflammatory changes in the groups treated with dexamethasone and TA-383. These findings suggest that the histopathological examination of the joints of the animal model is useful for the evaluation of anti-rheumatic drugs, and that TA-383 has suppressive effects on type II collagen-induced arthritis, an animal model for human rheumatoid arthritis.