We report two infants with eosinophilic gastroenteritis (EG). This rare disease can mimic the clinical symptoms and US appearance of idiopathic hypertrophic pyloric stenosis (IHPS). US examination of the antropyloric region with a high-frequency linear transducer can assist in the differentiation of EG from IHPS, which is important because the therapeutic approaches are completely different. Eosinophilic gastroenteritis should be considered in the differential diagnosis of IHPS, especially when there has been an ineffective pyloromyotomy.