Situs inversus abdominis is a rare congenital condition commonly associated with serious cardiac and splenic malformations. The importance of recognizing the presence of situs inversus abdominis preoperatively is emphasized by the fact that the surgical incision is placed on the incorrect side of the abdomen. A 6 day-old girl was referred to our hospital because of bile stained vomiting. A plain radiography of abdomen and chest showed the heart to be normal position and a reversed "double-bubble" picture with no other gas shadow in the rest of the abdomen. Abdominal computed tomography scan revealed situs inversus with the stomach and polysplenia on the right side and the liver on the left side. A laparotomy confirmed the diagnosis of situs inversus with duodenal atresia. The obstruction was bypassed by constructing a side-to-side duodenoduodenostomy. The postoperative course was uneventful.