Eighty-four patients who were endoscopically confirmed to have healed duodenal ulcers were entered into this 1-year, double-blind, placebo-controlled trial of sucralfate, 1g twice daily, in the prevention of duodenal ulcer recurrence. Patients remained in the study until recurrence of ulceration was endoscopically confirmed. Sixty-one patients could be evaluated for efficacy of treatment. Within 6 months, 23 of 31 placebo patients (74%) and 6 of 30 sucralfate patients (20%) had ulcer recurrence. At 12 months, 25 of 31 placebo patients (80%) and 8 of 30 receiving sucralfate (27%) had ulcer recurrence. The lower rate of ulcer recurrence in patients receiving sucralfate was significant (p = 0.0001). Survival curves also showed that sucralfate was significantly more effective in preventing relapse (p = 0.0001). Three patients were judged as experiencing drug-related side effects, two of which were in the placebo group. The results indicate that sucralfate is significantly more effective than placebo in the prevention of recurrence of duodenal ulcer disease.