Back ground: Biliary atresia is a relatively rare obstructive condition of the bile ducts causing neonatal cholestatic jaundice. The incidence varies and has a geographic pattern of occurrence. For example, in Europe the incidence is one in 18,000 live births, while it is one in 9640 live births in Japan. Portoenterostomy (Kasai) has become a popular operation of choice for non-correctable type of biliary atresia since 1959.Nowadays, upper GI endoscopy is a safe popular procedure in pediatric group age in expert hands, although some complications are still reported. In one study in 2006 by Kalpesh Thakkar et al (Vol 63, No 5, 2006, GIE journal AB 95, 586), from 10236 procedures performed in 9234 patients, immediate complications were reported in 239 procedures (2.3 %) the most common complication were hypoxia(157,1.5 %), bleeding (28,0.3 %) respiratory distress (9, 0.09 %), wheezing (9,0.09%), arrhythmia (7, 0.07 %), (nausea and vomiting (6, 0.06%). No perforation and death were reported. Complication rate was significantly higher in youngest age group.In this article we present a neonate who had underwent Kasai operation and developed an immediate serious life threatening complication after undergoing diagnostic upper GI endoscopy for upper GI bleeding 6 days after the operation.Case:A 3 week old girl newborn presented with prolonged cholestatic jaundice compatible with biliary atresia according to liver biopsy. She underwent Kasai operation. One week after surgery significant bright upper GI bleeding occurred. She underwent diagnostic upper GI endoscopy to find out the source of bleeding. Just after the procedure, her general condition got worse and the abdomen becamedistended. Plain abdominal x-ray showed free air in abdominal cavity. Emergent abdominal cavity exploration was performed. The porta hepatis anastomosis was disrupted for about 80% of its circumference due to gas insufflation pressure during diagnostic upper GI endoscopy. Redo porta hepatis anastomosis was done, end to side eneroenterostomy was intact. The patient was discharged after 6 days in a good condition. In six years follow up, she had acceptable condition, despite elevated liver function tests and hepatomegaly. She didn’t need hepatic transplantation at that time.Take home message:Although upper GI endoscopy in children is a safe procedure in expert hands, it has some potential complications. Perforation due to gas insufflation in this procedure is a very rare complication. Gastroenterologists should be informed of this possibility in early post-operative days by the surgeon before performing this procedure in cases who have underwent GI anastomosis.