There is a complex association between obesity, hiatal hernia (HH), and reflux. There is a deficiency of literature on the accuracy of preoperative high-resolution manometry (HRM) in detecting HH before both primary and revision bariatric surgery. A retrospective analysis of a prospective database of all HRM performed before bariatric surgery from 2014 to 2019. An electronic medical records review was conducted. Sensitivity, specificity, and global diagnostic test accuracy were calculated. Sixty-seven patients with HRM (mean age of 44.0 ± 11.3 years, body mass index 40.8 ± 6.9 kg/m2) were eligible. Intraoperative diagnosis of HH was made in 37 patients (55.2% prevalence). The HRM sensitivity was 48.7% (95% confidence interval (CI) 31.9-65.6%), specificity 90.0% (95% CI 73.5-97.9%), and accuracy was 67.2% (95% CI 54.6-78.2%). Comparing primary (28) and revision (39) surgery, the sensitivity (37.5% vs 57.1%), specificity (75.0% vs 100%), and diagnostic accuracy (54.3% vs 76.3%) were comparable, with overlapping 95% CI. Endoscopy performed in 30 patients had a sensitivity of 25.5% (95% CI 6.8-49.9%), specificity of 100% (95% CI 75.3-100%), and accuracy of 57.8% (95% CI 38.5-75.5%) and was comparable to HRM. High-resolution manometry for the detection of HH before bariatric surgery has a high specificity and maintains a high accuracy in both primary and revision bariatric surgery.