The present work was done to investigate the possible effects of 3,4-oxo-isopropylidene-shikimic acid (ISA) on acetic acid (AA)-induced colitis in rats. Colitis was induced by intracolonic injection of 6 % AA. Several parameters, including macroscopic score and biochemical parameters, were determined to assess the degree of protection. Biochemical parameters such as myeloperoxidase (MPO) activity, malondialdehyde (MDA) and nitric oxide (NO) levels, and superoxide dismutase (SOD) and inducible NO synthase (NOS) activities were measured following standard assay procedures. The study showed that treatment of rats for 6 days with ISA (100 and 200 mg/kg) was able to give complete protection against AA-induced colitis. Moreover, biochemical changes were reversed and brought toward control. These results suggest a beneficial effect of ISA against experimental colitis and the possible mechanism of the protective effects may be partly due to an antioxidant action.