With more and more extreme premature and very low-birth weight babies being resuscitated, umbilical central venous catheterisation is now being used more frequently in neonatal intensive care. One of the life-threatening complications is pericardial effusion and cardiac tamponade; however, it is potentially reversible when it is caught in time. The authors present a case of cardiac tamponade following umbilical venous catheterisation in a neonate. The patient was diagnosed at the appropriate time by echocardiography and urgent pericardiocentesis proved lifesaving.