Background: We aimed to perform a pre-post-test study to determine the prevalence of esophagitis assessed by anatomopathology study in obese patients undergoing laparoscopic sleeve gastrectomy (LSG). Methods: Retrospective quasi-experimental study design without a control group (one-group pre-post-test) conducted in a private Peruvian clinic. We included obese patients who (i) underwent LSG from January 2013 to December 2016 and (ii) underwent anatomopathological assessment of the esophagus before and one year after LSG. The McNemar’s test was used to perform the paired analysis. Results: We selected 239 patients who met the inclusion criteria. Preoperatively, the proportion of esophagitis slightly differed between the Los Angeles classification (73.22%) and anatomopathological assessment (69.87%). Morbid obesity (p<0.001) and metabolic syndrome (p<0.001) were more frequent in men. While the prevalence of anatomopathologically-confirmed esophagitis significantly decreased from the preoperative to the postoperative period (p=0.017), the prevalence according to the Los Angeles classification did not significantly decrease (p=0.664). The prevalence of anatomopathologically-confirmed esophagitis significantly decreased in men (p=0.047) but not in women following LSG (p=0.211). Conclusions: We reviewed the effects of LSG on anatomopathological esophagitis in obese patients. Our results suggest that LSG could reduce the prevalence of this complication; moreover, gender may have a role in the association. Literature is mixed, and surgeons must take a shared decision with the patient based on effectiveness, adverse events and cost-effectiveness.