The case of an eleven-months-old girl is reported: she entered the intensive care unit for fever, vomiting and left pleural effusion. Abdominal echography, CT scan and colonic opacification led to the diagnosis of a colonic Bochdalek hernia. A review of the literature showed that colonic hernias are rare, with only five previous reported cases in which colon was found in the thorax. The authors emphasise that there is a high risk of misdiagnosis due to the fact that small intestine contrast studies are normal; only colonic contrasting may lead to the right diagnosis. The roles of echography and CT scan are discussed.