Natural products and anti-inflammatory agents including cyclooxygenase-2 (COX-2) inhibitors which is a type of nonsteroidal anti-inflammatory drugs (NSAIDs) are highly considerable interest for the prevention of carcinogenesis. The objective of this study is to evaluate the oxidative status of colitis-associated cancer induced by azoxymethane (AOM)/dextran sulfate sodium (DSS), and the effects of COX-2 inhibitor in mice. Totally 40 mice were randomized and divided to four groups. All animals except control and Cox-2 inhibitor alone group received AOM/DSS to establish colitis-associated cancer model as reported elsewhere. COX-2 preferential inhibitor meloxicam was used to minimize side effects such as gastrointestinal hemorrhage. Meloxicam were used (5mg/kg, intraperitoneal) three times a week with meloxicam alone and AOM/DSS + meloxicam group. Superoxide dismutase (SOD), Glutathione peroxidase (GPx), Malondialdehyde (MDA) and Advanced Oxidation Protein Products (AOPP) which all of them are oxidative stress markers were measured by spectrophotometrically. The combination treatment of Meloxicam and AOM/DSS significantly increased (P<0.05) SOD activities in mice. GPx activities were found significantly increased (P<0.05) in Meloxicam and AOM/DSS combinations or alone. There were no differences between the control and treatment groups of MDA levels. AOPP levels of Meloxicam and AOM/DSS combination group were found higher than the other groups. Meloxicam and /or AOM/DSS treatment not caused lipid peroxidations, but increased the antioxidant enzymes and Advanced Oxidation Protein Products levels.