Purpose:To identify theeffect of Antacid calcium-preparation on gastroeosophageal reflux disease by using pH meterfor 24 hour monitoring analysis. Study methodology:A randomly controlled test was used for the study. Study objects were administered Antacid calcium-6 preparation and their gastric acidity level was identified by pH monitoring analysis for 24 hours. Theimpact of preparation in regards with before and after treatment and their relationship were analysed by t-test. Results:The 24-hour pH meter analysis of Antacid calcium-6 preparation indicated that before administration of preparation the gastroeosophageal pH=5,75±0,14, which has increased after the administration to pH=9,7±0,02 and the average duration was 7,8±0,09 days. In other words, the alkalinizing effect was statistically significant (p<0.001). Also, According to the criteria developed by the DeMeester, the daily prevalence of reflux, the prevalence of reflux that continued for more than five minutes and the DeMeester index indicated that the preparation was significantly efficient (p=0.041). The neutrialising effect of the preparation was established by using the criteria method developed by G.A. Agafonova and A.P. Kholopov (1984), and after administering the preparation, the gastric level was pH=4,6±1,5 indicating that the preparation had a neutralising effect. The average duration for neutralization was 19,3±0,9 hours. Conclusion: Аntacid calcium-6 preparation was effective in neutralising the gastric acidity and it was appropriate for treatment of GERD, chronic gastritis.