In 1905, John Edkins (1863–1940) undertook the studies of gastrin that have subsequently formed the basis for a century of investigation into the physiological basis of acid secretion and led to the elucidation of a variety of acid-suppressive pharmacological agents that have revolutionized the management of acid peptic disease. Although his name is known to few, his contributions to the physiology of gastric secretion and his study of spiral organisms in the stomach were prescient and to this day remain models of insightful and rigorous research. As a mentor, his educational impact was exemplified by the fact that he was the first to teach physiology to women in the United Kingdom. Gastrin has evolved from an initially unaccepted phenomenon, to be recognized as an important hormone and a fundamental component of regulatory biology as well as a clinically relevant biomarker of disease. Its critical role in the modulation of acid secretion has become a sine qua non and has been extended to include a broad regulatory proliferative role in the mucosa of the gastrointestinal tract. The pivotal role of gastrin in gastric physiology, biology and clinical medicine is now well accepted and reflects the fundamental contributions that Edkins made to the identification of the agent and the elucidation of its function. As a result of the delineation of the neural and hormonal regulatory mechanisms of acid secretion, the scientific basis of acid peptic disease has become apparent. The identification of histamine receptors and proton pumps has led to the discovery of novel pharmacotherapeutic agents capable of producing acid suppression of such efficacy that surgery has become virtually obsolete in the treatment of the disease process. A century after the initial observations by Edkins of gastrin, the identification of Helicobacter pylori and the ability to eradicate it, as well as the use of the proton pump inhibitor class of drugs, have revolutionized the management of gastroduodenal ulceration and gastroesophageal reflux disease. Both patients and physicians owe a great debt to Edkins, whose seminal observations regarding gastrin initiated an era of gastrointestinal scientific, clinical and pharmacological advance that has culminated in the ability to treat and cure acid peptic disease.