The effect of rice bran hemicellulose (RBH) on 1,2-dimethylhydrazine- (DMH) induced intestinal carcinogenesis was studied in male Fischer 344 rats. Rats were fed a basal control diet or a diet containing 2% or 4% RBH at five weeks of age. At 6 weeks of age, all animals were given an intraperitoneal injection of DMH (20 mg/kg body wt) at weekly intervals for 20 weeks and autopsied 7 weeks after the last injection. The incidence of DMH-induced colon tumors was significantly lower in rats fed the 4% RBH diet than in rats fed the basal control diet (p < 0.05). The number of colon tumors per rat was also significantly lower in rats fed the 4% RBH diet than in rats fed the basal control diet (p < 0.05). The present study suggested that the water-soluble RBH played a preventive role in DMH-induced large bowel carcinogenesis in Fischer 344 rats.