Incidence of pneumopericardia in neonates has reduced significantly since the routine administration of surfactant and synchronised modes of ventilation. The majority now occur secondary to the more common air leaks, e.g. pneumothorax, pneumomediastinum, pulmonary interstitial emphysema (PIE); although there are case reports of spontaneous pneumopericardia in the absence of known risk factors. In most cases the air will resorb without active management but if a tension pneumopericardium develops urgent drainage is required to prevent cardiovascular compromise and death. We present a rare case of iatrogenic tension pneumopericardium in a preterm baby secondary to chest drain insertion for a pneumothorax. The resulting air leak was sufficient to require surgical repair via a median sternotomy. This is a previously unreported complication of chest drain insertion in a neonate, and highlights the importance of careful drain placement.