In the present work, the antiarthritic activity of hautriwaic acid is reported. This ent-clerodane diterpene isolated from Dodonaea viscosa was evaluated in mice using a kaolin/carrageenan-induced monoarthritis model. The inflammation observed in the joint (knee) on days 1-8 ranged from 50-70 %. After 10 days of treatment with different doses of hautriwaic acid (5, 10, 20 mg/kg), a decrease in knee inflammation was detected. This recovery was observed with both reference drugs, methotrexate (1 mg/kg) and diclofenac (0.75 mg/kg). In these groups of mice, the concentration of proinflammatory cytokines interleukin-1 beta, interleukin-6, and tumor necrosis factor alpha in the joint was significantly lower than that of the negative control group (animals with damage without any treatment). The negative control group presented a decrease in the concentration of interleukin-10, while the groups that received hautriwaic acid at different dose exhibited an increase in this interleukin. This anti-inflammatory cytokine was not modified in the joint of mice with diclofenac, but in mice that received methotrexate, a significant decrease was observed. Hautriwaic acid isolated from D. viscosa diminished the joint edema induced by this mixture of polysaccharides (carrageenan), possibly by acting as immunomodulator of the inflammatory response. Georg Thieme Verlag KG Stuttgart · New York.