Insertion of central venous catheter is the most common invasive procedure in the neonatal intensive care unit. Indications for the usage of these catheters are countless and the most important are parenteral nutrition, infusion of fluids, blood sampling, parenteral administration of drugs, and invasive hemodynamic monitoring. Besides the great benefits brought on by the application of these catheters, complications caused by their use are numerous, and some of them are often life-threatening such as catheter-related bloodstream infection, pericardial effusion with or without cardiac tamponade, pleural effusion, liver injury and catheter-related thrombosis. Simple precautions taken during the insertion, vigilance on the maintenance, and proper catheter position is of paramount importance to avoid development of severe complications. They should be removed as soon as they are no longer needed. This graduation thesis discusses various aspects of central venous catheterisation in newborn infants, using umbilical venous catheters and peripherally inserted central venous catheters, including the results of a retrospective review study among hospitalised neonates at the Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital Centre Zagreb, University of Zagreb Medical School, with special emphasis on catheter-related complications.