Objectives To observe the effects of herbal steam-wash therapy on knee osteoarthritis(KOA),in terms of WBC, IL-1β and TGF-β1 concentrations. Methods 9 SPF old cynomolgus monkeys as KOA animal models were randomly divided into a steam-wash group (n=3), a traditional group(n=3) and a control group(n=3). Other 6 SPF youth cynomolgus monkeys were selected as a healthy group. The left knee of cynomolgus monkeys in the steam-wash group or traditional group were treated with herbal steam-wash therapy or traditional herbal compress therapy for 6 weeks, separately. The WBC, IL-1β and TGF-β1 concentration were detected from joint irrigation fluids before treatment and 2 weeks, 4 weeks, 6 weeks after treatment. Analysis of variance for repeated data was performed. Results (1)Articular cartilage degeneration of aged cynomolgus monkeys could be seen by HE staining; (2) In regard to WBC and IL-1β concentration before treatment, the steam-wash group, traditional group and control group compared with the normal group was significantly decreased (P<0.05). On the contrast, the concentration of TGF-β1 increased significantly (P<0.05). (3) At 2 weeks, 4 weeks, 6 weeks after treatments, WBC and IL-1β concentration decreased significantly than those before treatments in the steam-wash group and traditional group (P<0.05). (4) In regard to WBC and IL-1β concentration at 2 weeks, 4 weeks, 6 weeks after treatments, the steam-wash group and traditional group compared with the control group were significantly decreased (P<0.05), which decreased more in the steam-wash group compared with the traditional group (P<0.05). (5) The TGF-β1 concentration increased significantly at 2 weeks and 4 weeks after treatments (P<0.05). (6) In terms of TGF-β1 concentration at 2 weeks, 4 weeks after treatments, the steam-wash group and traditional group compared with the control group were significantly increased (P<0.05), which increased more in the steam-wash group compared with the traditional group (P<0.05). Conclusions The IL-1β, TGF-β1 concentrations and WBC in the knee joint fluids from cynomolgus monkey models of KOA were abnormal. Herbal steam-wash therapy and traditional herbal compress therapy could decrease the IL-1β concentration and increase the TGF-β1 concentration in knee joint, which is helpful for treatment of KOA. Moreover, the effect of herbal steam-wash therapy is better than traditional herbal compress therapy.