Results. Our data showed that mud treatment had no effect on antigeninduced arthritis after a 7-day treatment. However, leukocyte infiltration was significantly impaired in the joints of rats with zymosan-induced arthritis treated with mud compared with both untreated rats or rats treated with hot water. This effect was followed by a partial protective effect on the synovium and cartilage that was also observed in the rabbit osteoarthritis model. Conclusion.The Brazilian mud employed in our study presented an antiinflammatory effect on animal models of chronicle arthritis, reducing cartilage degradation. Even though the mechanism responsible for the observed effects is presently unknown, our data suggest that mud therapy may be useful as a complementary approach to treat chronicle articular diseases.