Context: A solution of simethicone administrated orally before the scan endoscopy procedure is recommended as a good means to reduce the bubbles interference. Aims: To evaluate the reliability, reproducibility and effectiveness of simethicone pre-treatment before endoscopic exploration of patients not diagnosed with malignant digestive pathologies. Methods: The study was organized in two stages. Time zero was a retrospective reanalysis of data from 58 randomized patients (age 15-90 years) who had been evaluated by endoscopy without simethicone (Control group), and 66 patients (Simethicone group) who were recruited and received 62 mL of a simethicone pre-preparation drink, 30 min before examination. The second stage, using procedure with simethicone, was continued and after 6 months at the beginning, 88 subjects were randomized. Stability in the results was demonstrated with simethicone. Statistical analysis was performed using SPSS v.21. Results: Analysis of comorbidities were represented with the highest prevalence being high blood pressure, diabetes mellitus, long-term depression, obesity and hypothyroidism. Results demonstrated similarity among endoscopist and between analysts within the same group (examination time, images resolved and with the best quality, by mucosal areas). However, these variables were different between groups, such that valuation quality was improved with simethicone, even 6 months after the initial evaluation. Conclusions: Use of simethicone as a pre-preparation drink 30 min before the endoscopy evaluation improves the quality of images and reduces the time of operation.