Background: Predictive factors of evolution or appearance of gastroesophageal reflux disease (GERD) after sleeve gastrectomy (SG) have not been identified to date. We aimed to assess the evolution of GERD symptoms 1 year after SG and to determine preoperative predictive factors using high-resolution manometry (HRM) and ambulatory 24-h esophageal pH monitoring (APM). Methods: We included 160 patients who underwent SG between 2013 and 2017 and performed preoperative APM and HRM. Positive APM was defined according to the Lyon consensus. Symptoms of GERD, proton pump inhibitors (PPI) use, weight loss (WL), and diet were recorded in all patients before and 1 year after surgery. Results: One year after surgery, 58 patients (36.3%) complained of GERD symptoms compared to 52 patients (32.5%) preoperatively (p=0.48). Among patients with preoperative GERD symptoms, only 26/52 patients (50%) still had symptoms, whereas 32/108 (29.6%) asymptomatic patients developed de novo GERD symptoms after surgery. PPI use increased after surgery reaching 36.9% of patients against 15.0% before (p<0.0001). Only preoperative symptoms of GERD were predictive of postoperative symptoms (OR= 2.47 [1.14-5.45]; p=0.023) in multivariate analysis. Preoperative manometric parameters, postoperative diet, and WL were not related to postoperative symptoms. In asymptomatic patients before surgery, silent GERD (positive APM without symptom) was predictive of postoperative GERD symptoms (OR=2.69 [1.00-7.25]; p=0.049). Conclusion: Evolution of GERD symptoms after SG reveals improvement for half of the patients and de novo GERD symptoms in one-third of patients. Predictive factors of postoperative symptoms are preoperative symptoms and positive preoperative APM in asymptomatic patients.