In both adjuvant arthritis and rheumatoid arthritis, edema and inflammation appear in synovial joints. Edema or effusion reflects an imbalance in lymph dynamics. Purified micronized flavonoid fraction is mainly used in the treatment of chronic venous insufficiency. This compound improves lymphatic drainage with a significant increase in lymphatic flow and lymphatic pulsality. It is suggested that the beneficial effect of purified micronized flavonoid fraction may be involved in the treatment of adjuvant arthritis in rats. In this study treatment of adjuvant arthritis in rats with Detralex, methotrexate, and their combination were evaluated. Groups of rats with adjuvant arthritis were treated with methotrexate (0.6 mg/kg/week), Detralex (20 mg/kg/day), and their combination for 50 days from adjuvant application. Hind paw swelling, arthrogram scores, serum albumin level, serum nitrite/nitrate concentrations, and whole-body mineral density were evaluated as markers of inflammation and destructive changes associated with arthritis. Long-term prophylactic treatment with low-dose methotrexate significantly inhibited the markers of both inflammation and arthritis. Detralex administered alone slightly decreased both the hind paw swelling and the arthritic score. Other inflammatory and arthritic markers were not significantly influenced. However, Detralex combined with methotrexate markedly potentiated the beneficial effects of methotrexate, which resulted in a more significant reduction in hind paw swelling, arthritic scores, and serum concentrations of nitrite/nitrate. Interestingly, the arthritis-induced decrease of bone mineral density in AA rats was significantly lower only in the group treated with the combination of Detralex and methotrexate. Our results indicate that Detralex increased the therapeutic efficacy of methotrexate basal treatment in AA. We suggest that this may be related to the beneficial effect of Detralex on microcirculation, especially on venules and lymphatic vessels.