H. pylori is a major cause of primary chronic gastritis and peptic ulcer disease in children. The authors give an account of H. pylori infection (cagA+, vacA+) in a 15-year-old girl where the initial clinical features included fatigue, collapses, and anorexia, elevated serum gastrin level (> 1000 mIU/l) raised the suspicion of gastrinoma. H. pylori gastric infection was also associated with iron-deficiency anemia. After treatment for H. pylori infection (omeprazole, clarithromycin, amoxycillin), clinical symptoms improved consistently, the serum gastrin level was repeteadly quite normal and hematologic and iron profiles were within the normal range. There is compelling evidence that H. pylori must be taken into account as a cause of hypergastrinemia other than gastrinoma in childhood.