AIM: Abdominal breathing recently has demonstrated an important role in managing symptoms of Gastroesophageal Reflux Disease (GERD), improving quality of life, medication adherence, and sleep quality. This study aimed to evaluate the effectiveness of abdominal breathing on sleep and quality of life in patients with non-erosive gastroesophageal reflux. SUBJECT AND METHODS: A Quasi-experimental design was used. A purposive sample of 100 patients was selected from the medical outpatient clinics of Menoufia University Hospital and the outpatient clinics of the National Liver Institute in Menoufia Governorate, Egypt. A Structured interview questionnaire was used to collect data on patients' sociodemographic characteristics, belly breathing exercise performance and self-reported compliance, GERD symptoms severity and frequency, Pittsburgh Sleep Quality Index, and GERD Health-Related Quality of Life. RESULTS: The frequency of GERD symptoms decreased from 26.64 pre-intervention to 17.61 and 9.58, respectively, at two- and four-months post-intervention. Antacid consumption among patients taking it 7 days/week was reduced from 34% pre-intervention to 2% and 0% post-intervention by two and four months, respectively. Good sleepers were 24% pre-intervention then increased to 62% and 90% post-intervention by 2 and 4 months, respectively. Regarding GERD related quality of life, only 1% was satisfied pre-intervention, which increased to 32% and 72% post-intervention by 2 and 4 months, respectively. CONCLUSION: Abdominal breathing offers better therapeutic improvements in all patients' outcomes such as reduced severity and frequency of GERD symptoms, reduced antacid consumption, increased sleep quality, and increased satisfaction with life quality. Healthcare professionals are encouraged to incorporate abdominal breathing into treatment protocols for patients with non-erosive GERD.