Ranitidine 150 mg twice daily (BID) is an approved therapeutic approach for relieving the symptoms of gastroesophageal reflux disease. Ranitidine 150 mg four times daily (QID) and cimetidine 800 mg BID are indicated for endoscopically diagnosed erosive esophagitis. This 12-week, randomized, multicenter trial involving 696 patients compared ranitidine 150 mg BID and ranitidine 150 mg QID with cimetidine 800 mg BID in healing erosive esophagitis. Healing rates, as determined by endoscopy, at 4, 8, and 12 weeks were comparable with ranitidine 150 mg BID (38%, 56%, and 71%, respectively) and cimetidine 800 mg BID (37%, 52%, and 68%, respectively), as were reductions in heartburn frequency and antacid consumption. However, ranitidine 150 mg QID produced significantly higher healing rates (49%, 67%, and 77%, respectively) and greater reductions in heartburn frequency and antacid consumption than cimetidine 800 mg BID. All treatment regimens were well tolerated. Thus ranitidine 150 mg BID is as effective as cimetidine 800 mg BID, and ranitidine 150 mg QID is more effective than cimetidine 800 mg BID in healing erosive esophagitis and reducing heartburn frequency and antacid consumption.