Objective: Protrusion of colonic mucosa to the lumen is called polyp. Since adenomatous polyps are neoplastic polyps, determining the factors contributing to the pathogenesis of the disease would be helpful in terms of reducing mortality and morbidity. Variety studies have showed that increased oxidative stress might play an important role in carcinogenesis. The aim of this study was to investigate the relationship between adenosine deaminase, xanthine oxidase nitric oxide, uric acid levels and oxidative stress in patients with colonic polyps to help the elucidation of pathophysiology of the disease. Methods: The study was conducted at Gastroenterology Clinics of Namik Kemal University Training and Research Hospital. Thirty-five subjects who underwent colonoscopy because of any gastrointestinal symptom and whose pathologic evaluation of colonoscopic biopsy revealed adenomatous polyps were enrolled as patient group. Control group was consisted of 36 healthy subjects. Uric acid was measured by an autoanalyzer using photometric method. Adenosine deaminase, xanthine oxidase, and nitric oxide were measured manually using a spectrophotometric method. Results: Xanthine oxidase, uric acid, and nitric oxide levels were found to be significantly higher in patients with colonic polyp compared that of the healthy controls. (p = 0.007; p = 0.02; p<0.001, respectively).Although adenosine deaminase levels were significantly higher in patient group, the difference was not statistically significant (p = 0.07) Conclusion: Increased serum levels of adenosine deaminase, xanthine oxidase, nitric oxide, and uric acid levels in patients with colonic adenomatous polyp may indicate the increased oxidative stress and the oxidative impairment of the colonic mucosa which may play an important role in the pathophysiology of the disease. Further studies would be useful to assess antioxidant treatment options in these patients.