A 11-month-old boy presented with a 4-month history of failure to thrive. His initial presentation was highlighted by fever, postprandial abdominal pain and lethargy. The diagnosis was elusive despite extensive investigations. A contrast enhanced abdominal computerised tomogram (CT) suggested the presence of a pancreatic pseudocyst. At laparotomy, a lesser sac collection was drained and the patient's general condition improved. Three weeks postoperatively, the symptoms recurred and a second contrast enhanced abdominal CT revealed a duodenal duplication cyst. A 6.5-cm duodenal duplication cyst communicating with the fourth part of the duodenum was resected in its entirety with resolution of the patients' symptoms and establishment of adequate growth.