Three male newborns, born at 30 weeks, 36 weeks and at term, respectively, developed serious complications related to umbilical venous catheters. The first patient had persistent bacteraemia due to a cardiac thrombus. He recovered after treatment. In the second patient, the umbilical venous catheter was placed in the pericardial sac, causing accumulation of parenteral nutrition and fatal cardiac tamponade. In the third patient, the umbilical catheter was positioned in the liver, leading to extravasation of parenteral nutrition in the liver and peritoneal cavity. At follow-up, he had developed an atrial septum defect, hypotonia and developmental retardation. Umbilical venous catheterisation has been used in neonatal intensive care units for more than 50 years to allow continuous infusion of medication, fluids and nutrition. However, the use of umbilical venous catheters can be associated with severe infectious, thrombotic and traumatic complications. Therefore, umbilical venous catheterisation requires a critical assessment of the need, alternatives and possible complications.