We report on a case of a secondary right-sided diaphragmatic hernia following group B streptococcal (GBS) septicaemia in a very low birth weight infant born at 30 weeks. After initial improvement, the diagnosis of a secondary right-sided diaphragmatic hernia was suspected with the persistent radiological pulmonary right-sided image on the chest x-ray and the clinical degradation. The diagnosis was confirmed by ultrasonography on day 43. The postoperative course was simple. Persistent respiratory distress in a neonate, after a GBS septicaemia associated with a right pulmonary opacity on the chest x-ray, should prompt a careful evaluation. A secondary right-sided diaphragmatic hernia should be considered. Treatment is surgery, the prognosis is good in the absence of pulmonary hypoplasia.