To determine its effect on intestinal tumorigenesis and the protumorigenic COX pathway in Apc(Min/+) mice, resveratrol was administered as a powdered admixture in the diet at 0, 4, 20, or 90 mg/kg body weight for 7 wk. In two separate experiments, resveratrol did not affect intestinal tumor load. It was stable in the diet under experimental conditions, circulated in the plasma as the glucuronide-conjugated form and reached the tumors as evidenced by significant decreases in PGE2 levels. However, immunohistochemical staining of intestinal tumors revealed no changes in COX-2 expression. This study demonstrates that resveratrol consumed ad libitum in the diet, does not modify tumorigenesis in Apc(Min/+) mice.