Enteric duplications are uncommon congenital anomalies. Duplications of the stomach account for only 3.8% of gastrointestinal duplication. More particularly, duplications involving the pylorus are extremely rare. These are characterized by firm attachment to at least one point of the alimentary tract with a well developed coat of smooth muscle and mucous membrane. The most frequent presentation is an abdominal mass with vomiting, mainly discovered during the first year of life. We experienced a 24-day-old boy with non-bilous, non-projectile vomiting and palpable abdominal mass, clinically similar to hypertrophic pyloric stenosis. He was diagnosed as having gastropyloric duplication cyst by abdominal ultrasonography, upper gastrointestinal series and abdominal computerized tomography. Thus we report a newborn infant with gastric outlet obstruction secondary to a duplication of the pylorus which is a rare cause of gastric obstruction.