Purpose: One concerning disadvantage of sleeve gastrectomy (SG) technique as a treatment for obesity is the risk of developing gastroesophageal reflux disease (GERD) or worsening its symptoms after surgery. The purpose of this study is to describe the changes in manometry and 24-h pHmetry with impedance in bariatric patients after SG. Materials and Methods: Retrospective analysis of 225 patients who underwent SG and were subjected to manometry, 24-h phmetry, and 24-h impedance between 2006 and 2016. Patients were subdivided into groups based on the test performed: 66 patients with manometry, 60 with 24-h pHmetry and 53 with 24-h impedance. Descriptive and analytical statistics were used for analysis. Results: Manometry results showed a decrease in LES pressure from 12.26 ± 6.87 to 8.88 ± 6.28 mmHg in patients after surgery, de novo LES incompetence in 53.33%, worsening of symptoms in 71.4%, increase of inverted gastroesophageal gradient from 6.06% to 48.48% (p<0.05), and a rise in esophageal dysmotility from 18.19% to 37.87%. 24-h pHmetry showed an increase of DeMeester score from 16.71 ± 12.78 to 42.88 ± 32.08 after SG and 79.48% of de novo GERD. Ambulatory 24-h impedance showed an increase of pathological reflux from 47.17% to 88.67% postoperatively. Conclusions: Laparoscopic SG is associated with a higher proportion of abnormal DeMeester score and greater incompetence of the LES in post-SG esophageal tests. Hence, SG may predispose the development of gastroesophageal reflux in the postoperative period.