Purpose Abnormal gastric neuromuscular function may contribute to gastroesophageal reflux disease (GERD). We assessed if gastric myoelectrical abnormalities measured by Gastric Alimetry® body surface gastric mapping were correlated with symptoms and reflux on 24-hour pH testing. Methodology Simultaneous Gastric Alimetry was performed on patients undergoing 24-hour pH-impedance testing for investigation of possible reflux symptoms. Tests consisted of the insertion of a pH catheter, followed by a standard 4.5 hr Gastric Alimetry test and symptom logging. Data were segmented into 15-minute epochs. Results Forty subjects were recruited (mean age 46.5 years, mean BMI 25.9kg/m², 60% female): 20 undergoing pH-impedance testing (12 diagnosed with GERD and 8 symptomatic patients without GERD), and 20 matched controls. GERD patients displayed more overall unstable gastric myoelectrical activity compared with controls (Gastric Alimetry Rhythm Index [GARI]: 0.43±0.16 vs 0.61±0.20, p = 0.011), but not compared to patients without GERD (0.57±0.14 vs 0.61±0.20, p = 0.605)). Decreasing overall GA-RI was associated with increasing DeMeester score (-0.46, p=0.042). There was no temporal correlation between GA-RI and percent time in reflux on pH tests (r=0.08, p=0.182), or with heartburn severity per epoch (r=0.04, p=0.309). However, periods of decreased GA-RI were temporally associated with increased nausea (r=-0.22, p<0.001) and excessive fullness (r=-0.28, p<0.001). Conclusion Reduced gastric rhythm stability is more common in GERD patients and correlates with increased overall acid exposure, although no temporal link to heartburn was found. Reduced rhythm stability was temporally associated with nausea and fullness.