Pneumoperitoneum is the presence of air within the peritoneal cavity. Pneumoperitoneum is said to occur more in neonates than in infants and most cases are idiopathic. However it may be caused by necrotizing enterocolitis (NEC), gastrointestinal tract perforation, iatrogenic causes such as mechanical ventilation and intrathoracic pathology (pneumothorax, pneumomediastinum). Plain abdominal radiograph has a good diagnostic value in evaluating patients with suspected pneumoperitoneum. Pneumoperitoneum can also be diagnosed using computed tomography (CT). A case of neonatal pneumoperitoneum without any established cause is reported due to its rarity. The approach to its management and radiological signs of pneumoperitoneum are also presented.