Background and aim: Transient lower esophageal sphincter relaxations (TLESRs) are the most important mechanism by which gastroesophageal reflux occurs and sleeve sensor manometry is the gold standard for detection of TLESRs. The aim of this study was to evaluate manometry with closely spaced sideholes (high-resolution manometry) for the detection of TLESRs as an alternative. Methods: In twelve patients with gastroesophageal reflux disease a 90-min postprandial manometry was performed using a catheter incorporating both a sleeve sensor and closely spaced sideholes in the esophagogastric junction. TLESRs recorded with both techniques were scored. Reflux during TLESRs was detected using manometry (common cavity), intraluminal impedance and pH monitoring. Results: A total of 145 TLESRs were detected using both techniques, 117 with high-resolution manometry and 108 with sleeve sensor manometry (NS). Manometric signs of reflux during TLESRs detected with high-resolution and sleeve sensor manometry were found in 62.4 and 56.5 % (NS) respectively, while 38.5 and 35.2 % (NS) on pH-metry and 70.1 and 60.2 % (NS) on impedance monitoring. TLESRs recognized only with high-resolution manometry were more often accompanied by reflux, as detected with manometry (59.5 %) and impedance monitoring (67.6 %), than TLESRs recognized only with sleeve sensor manometry (32.1 and 28.6 %). Conclusion: High-resolution manometry is at least as accurate as sleeve sensor manometry for the detection of TLESRs.