Gastroesophageal reflux is the leading factor of the pathogenesis of gastroesophageal reflux disease (GERD). A number of mechanisms (decreased pressure and transient relaxation of the lower esophageal sphincter, increased intraabdominal pressure, hiatal hernia) for its development are described. At the same time, the acid pocket occurring after meals is a source of reflux. The data available in the literature on the clinical relevance of the acid pocket in GERD and on the factors influencing its size and location are given. The efficacy of drugs used to treat GERD in terms of their effect on the acid pocket is shown. Proton pump inhibitors reduce the volume of the acid pocket and increase its pH, by affecting gastric acid production. Prokinetic agents are able to displace the acid pocket from the gastroesophageal junction. An alginate-antacid formulation combines the physical antireflux effect of alginate and the acid-induced neutralization of the acid pocket.