To evaluate the efficacy of Keonkangbujatang (KKBT) in osteoarthritis treatments, C57BL/10 mice were treated with papain to induce osteoarthritis, and anti-arthritic effects were measured. To ensure safety of the KKBT sample, ALT, AST, BUN, and creatinine levels were measured, and they were all within the normal range. Based on the fact that suppression of inflammatory cytokines leads to the improvement of arthritis, IL-1b, IL-6, TNF-a, and MCP-1 production levels were measured. The cytokines were significantly decreased in serum. Also, mRNA levels of IL-1b, IL-6, and iNOS-II were significantly decreased in joint tissues. PGE2, a usual inflammation vector, and LTB4, TXB2, that are involved in the onset and deterioration of inflammation, were all significantly decreased. The levels of white blood cells, neutrophiles, and mononucleophiles also decreased, although the numbers were not significantly large. I*mmune-modulation of KKBT in the pathological mechanism of cartilage deterioration by inflammatory cells and their vectors was proved. This study should provide basis for the development of effective therapeutics as well as use in clinical practice.