Summary Background & aims Percutaneous endoscopic gastrostomy (PEG) tube feeding is widely used for patients with swallowing dysfunction, and aspiration pneumonitis induced by reflux of gastric contents is one of the most frequent and life-threatening events in such patients. We performed this study to clarify the effect of half-solidification of nutrient on gastro-esophageal reflux (GER) of acidic and non-acidic gastric contents in patients with PEG. Methods The subjects were 14 elderly patients undergoing PEG feeding (female: 11, mean age 83.1 y). Twenty-four hour esophageal multichannel intraluminal impedance (MII) and pH (MII-pH) monitoring were performed during and after feeding with half-solid and liquid nutrient, respectively. The numbers of GER events during 4 h after the start of feeding were compared. Results There was no significant difference in the total number of GER events between half-solid nutrient feeding and liquid nutrient feeding (5.6 ± 1.5 vs. 6.6 ± 1.5). The number of acid reflux events after half-solid nutrient feeding tended to be higher than that after liquid nutrient feeding (1.9 ± 1.1 vs. 1.4 ± 0.8). Conclusion Half-solidification of nutrition does not appear to be effective for preventing GER caused by liquid PEG feeding.