As many as 89% of gastric ulcer patients experience ulcer recurrences within 1 year of successful healing with conventional antiulcer therapies. Because ranitidine is effective in the healing of gastric and duodenal ulcers and the maintenance of healed duodenal ulcers, we hypothesized that ranitidine would also be effective in the maintenance of healed gastric ulcers. A 48-week, placebo-controlled, randomized, double-blind, multicenter trial was conducted to compare ranitidine 150 mg administered at bedtime with placebo for the maintenance of healed gastric ulcers. Endoscopies were performed at baseline and repeated after 12, 24, 36, and 48 weeks of treatment. Gastric ulcer recurrence rates at each scheduled endoscopy were significantly lower in patients receiving ranitidine (5%, 13%, 16%, and 19%, respectively) compared with those receiving placebo (20%, 30%, 40%, and 50%, respectively). Compared with placebo, ranitidine was more effective in maintaining healed gastric ulcers regardless of previous gastric ulcer history, smoking status, age (< 65 vs > or = 65 years), or sex. There were no significant differences between the two treatment groups in the number of patients experiencing adverse events or laboratory abnormalities. Ranitidine 150 mg administered at bedtime provides safe and effective treatment for the maintenance of healed gastric ulcers.