A retrospective study was undertaken to examine the prognosis of gastric outlet obstruction with specific reference to patients with obstruction due to peptic ulcer. During the 10-year period 1970-1979, 68 patients with gastric outlet obstruction were admitted to our hospital. Obstruction was caused by peptic ulceration in 55 of these patients, all of whom initially were managed conservatively. Thirty-four, however, required surgical decompression during their first admission for obstruction, and 11 needed surgery for a subsequent episode of obstruction. Of the ten patients who have not undergone surgery, six died within 3 years of their first episode of obstruction and three of the four survivors continued to have recurrent obstructive symptoms. Overall, 92% (45/49) of patients who have lived for more than 3 years after their presentation with gastric outlet obstruction due to peptic ulcer have required surgery for relief of obstruction.