Background: Acid peptic disease is a common problem, with a similar prevalence of gastroesophageal reflux disease (GERD) in adults and children. The presentation of GERD in infants and children varies from crying, irritability, or sleep disturbance to feeding difficulties, vomiting, or rumination. Helicobacter pylori (HP)—related diseases and gastric and duodenal ulcers are much more common in adults than in children, who are more likely to have gastritis or duodenitis. However, because HP infection is most likely acquired in childhood, treatment of children with endoscopically documented active HP disease may minimize the potential risk for peptic ulcer or gastric cancer in adulthood, although this is yet to be proved. Objective: Omeprazole has been shown to be effective in the treatment of acid-related diseases. This paper reviews the literature on the use and administration of omeprazole for the treatment of GERD, peptic ulcer disease, HP infection, and other acid-related conditions in children. Methods: Studies were identified through searches of MEDLINE ® and Science Citation Index for the period 1986 to November 2000, and from the reference lists of identified articles. The search terms used included omeprazole, proton pump inhibitor (PPI), children, pediatrics, routes of administration, GERD, HP infection, esophagitis, and administration. In addition, the manufacturer of omeprazole was asked for relevant unpublished information. Results: Marketed and extemporaneous formulations of omeprazole have been administered to children aged 2 months to 18 years for the treatment of erosive esophagitis, gastric ulcer, duodenal ulcer, HP infection, and related conditions at dosages of 5 to 80 mg/d (0.2–3.5 mg/kg/d) for periods ranging from 14 days to 36 months with a low incidence of adverse effects. The initial dose most consistently reported to heal esophagitis and provide relief of symptoms of GERD appears to be 1 mg/kg per day. Conclusions: In uncontrolled clinical trials and case reports to date, omeprazole has been effective and well tolerated for the acute and chronic treatment of esophageal and peptic ulcer disease in children, particularly those who had failed to respond to previous treatment with histamine 2-receptor antagonists. Should future long-term, controlled clinical trials in children demonstrate safety and efficacy, this PPI is likely to find a place in the armamentarium of pediatric pharmacotherapy.