Antral gastrin cell hyperfunction is a rare condition, often associated with severe duodenal ulcer disease. In children, clinical and functional characteristics of this syndrome are poorly known. Two cases are described here: one child had melena and the other had moderate abdominal pain, both without peptic ulceration. Basal and postprandial increase of gastrin levels showed a response over the upper normal range, indicating gastrin cell hyperfunction. Acid hypersecretion, both basal and after pentagastrin stimulation, was also found in the two children, confirming the biological effect of their sustained hypergastrinemia. Gastrin cell counts were within the normal range, while the number of somatostatin D cells was significantly reduced. This report stresses the importance of diagnosing antral gastrin cell hyperfunction in children because this unrecognized condition may manifest with serious complications (bleeding) or nonspecific abdominal symptoms.