The present study investigated the effect of cranberries on development of colon tumors induced by azoxymethane in Fisher 344 male rats. Fifty five rats were divided into five groups and fed with control (AIN 93) or treatment diets: cranberry meal (5, 10%) cranberry juice (2.5, 5%). Two AOM (16 mg kg-1 b.wt.) injections were given weekly for 2 weeks for induction of colon tumors. At 45 weeks of age, all rats were killed and colons were evaluated for tumor incidence, size of tumor and tumor multiplicity. Selected hepatic phase 1 (CYP2E1), phase 11 (GST) and antioxidative enzyme (catalase and SOD) activities were determined. Tumor size and tumors/tumor bearing rat were higher (p<=0.05) in the control group. Number of tumors was lower in cranberry fed rats compared to control. Administration of cranberry to rats increased (p<0.05) hepatic enzyme activities by 1.2-3.7 fold compared to control fed rats. These results indicate that feeding cranberry (meal and juice) inhibited colon tumors induced by AOM and enhanced the activity of hepatic enzymes.