Long-term prostaglandin (PG) therapy has recently been associated with gastric mucosal hyperplasia. We reviewed the clinical and radiologic (especially sonographic) records of eight patients with complex congenital heart disease who were on PG therapy. Feeding problems, vomiting, and abdominal distension were present in six patients. Barium meal revealed antral narrowing in three patients, suggestive of hypertrophic pyloric stenosis in two. Sonography showed a variable degree of increased gastric mucosal lobulation often accompanied by a marked polypoid or lobular appearance. Cortical hyperostosis related to PG therapy was seen in three patients. PG-associated gastric mucosal hyperplasia can cause feeding problems and pronounced gastric lobulation.