Introduction: In most patients, gallbladder polyps, both benign and malignant, are usually an incidental finding. However, imaging studies cannot accurately establish their degree of malignancy. Objective: To determine the risk factors for gallbladder polyp malignancy in two Peruvian public hospitals. Methodology: Retrospective cohort study conducted on secondary data from patients who underwent cholecystectomy between 2004 and 2012 in Lima and another in Callao, Peru. The malignancy of the polyp was established according to the histopathological type of adenocarcinoma. Relative risks and their 95% confidence intervals (95%CI) were obtained. Moreover, ROC curves were used to determine sensitivity and specificity according to the size of the polyp. Results: Of 368 biopsies, 26 (7%) were adenocarcinomas. The median size of the polyps was 4mm (range: 1-65mm). 176 patients (51%) had multiple polyps, and 85 (23%) had associated gallstones. Multivariate analysis showed that the risk of malignancy increased by 26% (95%CI:14-40%, p-value:<0.001) per millimeter of polyp size and by 182% (95%CI:46-445%, p-value=0.002) based on vesicular wall size, adjusted for patient age, lithiasis and vesicular size. For a size of 6mm, sensitivity was 81%, and specificity was 85%. Conclusion: The size of the polyp and the thickness of the vesicular wall are associated with the malignancy of vesicular polyps.