Successful gastric freezing designed to achieve protracted periods of achlorhydria depends upon the attainment of uniform mucosal-temperature depression over the period of perfusion, an objective regularly achieved on freezing the isolated canine gastric pouch and the intact rodent stomach. This aim is facilitated by the use of four balloon-mucosal interface thermocouples, high collant flow rates, uniform coolant dispersion, perfusion with a nontoxic coolant, and rewarming of the stomach on conclusion of the procedure. Maintenance of balloon-mucosal interface temperatures in the range of -10 C to -11 C for six to seven minutes is optimal but not often registered on all thermocouples. Up to Jan 1, 1966, a total of 698 patients with manifestations of peptic ulcer and 10 patients with esophageal varices had undergone 1,021 episodes of freezing without hospital mortality. Postfreeze bleeding or gastric ulcer or both occurred in 7.5%. Since institution of rapid postfreeze gastric rewarming no complications have been observed. Almost uniform initial relief of pain and a high incidence of ulcer-crater healing were observed. Of those patients undergoing gastric freezing more than 24 months ago, 40% were either asymptomatic or experienced only minimal symptoms.