Fifty-three asymptomatic patients who, in spite of continuous treatment with ranitidine 300 mg bid for six months, had active severe oesophagitis, Savary and Miller grade III-IV or Barretts ulceration at endoscopy were treated with high dose famotidine. In the severe oesophagitis group famotidine 40 mg bid, 13/29 (44%) healed at eight weeks and 17/29 (58%) at sixteen weeks. In the Barrett's ulcer group famotidine 40 mg tid, 10/24 (41%) healed at eight weeks and 18/24 (75%) at sixteen weeks. Famotidine in high doses was well tolerated in this age group (mean 66.75 years), with 5/53 (9%) minor adverse events recorded. Famotidine in high dose is effective in the treatment of ranitidine resistant severe oesophagitis or Barrett's ulceration.