Effects of 70% ethanol extract of the stems and leaves of V. rotundifolia (VRE) on the activation of IgG2 and histology in collagen-induced arthritis (CIA) as a model of rheumatoid arthritis were examined. Histological changes in the knee joints were evaluated and determined the serum anti-type II collagen IgG2a and IgG2b levels in CIA. VRE treatment significantly decreased the arthritis index, the synovial cartilage erosion, and the serum IgG2a and IgG2b levels, suggesting that V. rotundifolia might be useful for treating rheumatoid arthritis.