Duodenal membranous atresia is a rare congenital disease. Here, we present a case of 6-month-old girl referred to us for repeated vomiting since birth. Milk scan was performed, and the results revealed a typical “double-bubble” sign. In addition, only very little activity was shown in the small intestine even at the end of the scintigraphy. These results led to the diagnosis of duodenal atresia, which was subsequently confirmed by gastroenterography and laparotomy. Our case demonstrated the potential value of milk scan in the diagnosis of this congenital disorder.