This article describes experience of the use of ranitidine in children with peptic ulcer and patients with pancreatic cystic fibrosis. Ranitidine proved to be efficacious and well tolerated, the percentage of healing being 89.4%. Ranitidine was also used in subjects with gastritis from Campylobacter pylori, obtaining rapid regression of subjective symptoms. Administration of ranitidine to cystic fibrosis patients improved the efficacy of the pancreatic extract, with consequent enhancement of digestive compensation.