OPINION STATEMENT:Hypersecretory conditions affecting the stomach account for significant morbidity and mortality manifested in some cases with peptic ulcer, gastrointestinal hemorrhage, and/or gastroesophageal reflux disease (GERD). The diagnosis of gastric acid hypersecretory states can be challenging and relies on the use of quantitative assays to measure gastric acid secretion and serum gastrin. The most common etiology for hypergastrinemia is the use of potent gastric acid inhibitors such as the proton pump inhibitors. The differential diagnosis of this condition is of critical importance, and will dictate management decisions. Conditions such as atrophic gastritis are relatively benign and can lead to hypergastrinemia without the presence of gastric acid hypersecretion. Zollinger-Ellison syndrome, on the other hand, causes hypergastrinemia with profound gastric acid hypersecretion . More common causes of hypergastrinemia include gastric outlet obstruction, ileus, and chronic renal failure . In most cases, proton pump inhibitors will be used to manage these conditions. In some instances, surgical therapy may be required. This chapter will review the important clinical causes of gastric acid hypersecretion and provide insights to the best medical management options to better care for patients with these disorders.