Introduction: Several studies suggest that acromegaly is associated with an increased risk of colon polyps and colorectal cancer (CRC). There is no consensus on the factors associated with its development. Objectives: To assess the prevalence of colon adenomas (CA), hyperplastic polyps (HP), CRC and colon diverticula (CD) in patients with acromegaly; to compare with the prevalence in the general population; to determine the relationship between colonoscopic lesions and growth hormone and insulin-like growth factor 1 levels, the duration of the disease and the presence of skin tags. Methods: Retrospective study with analysis of medical records of the patients, followed in Garcia de Orta hospital, between 1992 and 2012. Results: Thirty three patients with acromegaly were identified and 28 underwent at least one endoscopic examination. The prevalence of abnormalities found in this study versus data in the general population was: CA 14.3 versus 38% (p = 0.0098), HP 14.3 versus 9% (p = 0.33), CRC 7.1 versus 1% (p = 0.0012) and CD 21.4 versus 19% (p = 0.75). In patients with acromegaly and CRC the median disease duration (years) was 30 compared to 11 in the group without any colonoscopic lesion (p = 0.028). There were no significant differences in hormone levels or in the presence of skin tags. Conclusions: Patients with acromegaly had significantly less CA and more CRC than the general population. Disease duration was significantly higher in patients with acromegaly and CRC, compared to those with no colonoscopic abnormalities. There was no relationship between endoscopic findings and laboratory results or skin tags. This study highlights the risk of CRC in acromegaly and suggests the duration of the disease as one of the possible factors associated with the development of cancer. However, the limited number of patients prevents reaching valid conclusions and encourages the performance of studies at a national level. (C) 2013 Sociedade Portuguesa de Endocrinologia, Diabetes e Metabolismo. Published by Elsevier Espana, S.L. All rights reserved.