Diet-induced changes in the activities of bacterial enzymes are known to play a role in colon cancer development. Resveratrol has been implicated as a protective agent in carcinogenesis. In the present study, the effect of resveratrol on the activities of faecal and colonic biotransforming enzymes such as β-glucuronidase, β-glucosidase, β-galactosidase, mucinase, nitroreductase and faecal sulfatase activity was assessed. The total number of aberrant crypt foci and their distribution in the proximal, medial and distal colon were observed in 1,2-dimethylhydrazine (DMH)-induced rats (group 3) and other treatment groups (groups 4–6). DMH (0.02g/kg body weight) was given subcutaneously once a week for 15 consecutive weeks, and the experiment was terminated at 30 weeks. DMH-treated rats showed elevated levels of cancer-associated bacterial enzyme activities, whereas on resveratrol supplementation in three different regimens, rats showed lowered activities. Resveratrol supplementation throughout the experimental period (group 6) exerted a more pronounced effect (P<0�01) by modulating the development of aberrant crypt foci and the activities of bacterial enzymes than did the other treatment regimens (groups 4 and 5). Thus, the present results demonstrate the inhibitory effect of resveratrol on DMH-induced colon carcinogenesis in rats.