Heartburn is a frequent and sometimes initial complaint in hyperparathyroidism, and it is often relieved by successful parathyroid surgery. Four of five patients with primary hyperparathyroidism and heartburn obtained relief of symptoms and had an increase in lower esophageal sphincter pressure after successful operative treatment. Four of five volunteers undergoing calcium infusion exhibited a decrease in lower esophageal sphincter pressure after about 2.5 to 3 hours of infusion. Calcium infusion in a treated patient who had an increase in lower esophageal sphincter pressure postoperatively resulted in a transient return of lower esophageal sphincter pressure to preoperative levels.