Five hundred and fourteen high-risk neonates who had indwelling umbilical catheters at the neonatal intensive care unit of the University of Benin Teaching Hospital were studied. of these 514 neonates, 122 (23.8%) had their catheters in-situ for longer than 24 h. Of the 122, fifty-four (44%) had positive bacterial cultures from their catheter tips. Seven (5.7%) and four (3.2%) of the 122 neonates studied developed septicaemia and necrotizing enterocolitis respectively. Catheterization for periods in excess of 48 h significantly increased the risk of bacterial colonization. Malposition of umbilical catheter tips include: insertion into the right portal vein (thirty-six cases); superior mesenteric vein (three cases) and the left atrium (four cases). The complications related specifically to the malposition were: air collection in the hepatic venous system (two cases); cardiac arrest (one case); necrotising enterocolitis (one case) and a case of blanching of the abdominal wall. Because of these complications, the indications for catheterization should be restricted to carefully selected patients and strict aseptic technique be adhered to during the procedure.