Gastroesophageal reflux disease (GERD) is a very common medical condition. Symptom improvement from ingested prebiotic soluble fiber has not been reported previously. In fact, a related soluble fiber, fructooligosaccharides, has been shown to worsen GERD. We report on a series of 24 patients with GERD, 88% of which improved after several weeks of daily consumption of a specific maltosyl-isomaltooligosaccharide (MIMO) fermented prebiotic soluble fiber. We also report on 2 proton pump inhibitor (PPI)-dependent patients with GERD who, after beginning daily MIMO, were able to eliminate PPI therapy. The hypotheses explaining the mechanism for GERD improvement with MIMO is discussed. To the best of our knowledge, these cases are the first time any prebiotic soluble fiber has been reported to improve or eliminate symptoms of GERD and enable patients with GERD to decrease or eliminate their PPI therapy.