Aim: Evidence arising from experimental studies indicates an association between increased levels of the growth hormone/insulin-like growth factor 1 and oxidative stress. The association of the Ser326Cys polymorphism in the 8-oxoguanine glycosylase (OGG1) gene with a colon carcinoma and diabetes mellitus has been examined. The aim of the study was to compare the genotypic distribution of OGG1 Ser326Cys between acromegaly patients and nonacromegalic subjects and to explore whether this polymorphism is associated with a colon polyp risk and abnormal glucose tolerance. Methods: We examined 98 acromegaly patients, and 99 healthy subjects who can be compared in terms of age and gender. All participants were evaluated by anthropometric and biochemical measurements. Also, a 75-g oral glucose test and colonoscopy was applied to the patients. Genomic DNA was isolated from peripheral blood leucocytes and the genotype was assessed by melting temperature analyses after using a real-time polymerase chain reaction protocol. Results: Colon polyps were detected in 13 (30.2%) of 43 patients who underwent the colonoscopy. Except for diastolic blood pressure, clinical and biochemical characteristics were similar between the patients diagnosed with and without a colon polyp. A higher proportion of acromegaly patients had the Ser326Ser genotype when compared to the control group (p=0.007). Genotypes were similar between the patients with a normal glucose tolerance and an abnormal glucose tolerance (p=0.774). The frequency of the Cys allele was significantly higher in patients with polyps than those without a polyp (38.5% vs. 18.3%) (p=0.029). Conclusion: Our results suggest that the Cys allele may influence the colon polyp risk in acromegaly patients. Large-scale studies with acromegaly patients are required to show whether being a carrier of the Cys allele is associated with the risk of a colorectal polyp.