Catheter-related sepsis is commonly encountered in the neonatal intensive care unit. We retrospectively studied infants with vascular catheters at 2 NICUs. Data were obtained from the computerised admission records available at both the hospitals. Our aims were to describe the clinical and microbial profile of nosocomial sepsis in infants with vascular catheters [umbilical artery (UA), umbilical venous (UV), central venous Broviac (CV), percutaneously placed central venous (PC), peripheral artery (PA)], and to determine the association between catheter type, duration and sepsis in a subset of the population. Nosocomial sepsis (positive blood culture after the 3rd postnatal day) occurred in 217 of 2091 (10.4%) infants. Infected infants, in contrast to non-infected, had a significantly (P < 0.001) greater number of multiple catheters (2.3 vs 1.4) had lower birth weights (1.2 vs 2.1 kg), were younger (28 vs 33 weeks) and had lower 1 and 5 minute Apgar scores (4.3 and 6.7 vs 5.5 and 7.4). The most common organism was coagulase negative Staphylococcus. In a subset population as analyses revealed, longer duration of UA use was associated with higher infection rates [13.6% with UA use for > or = 8 days vs 1.3% for < or = 7 days (P < 0.0001)]. PC use had a lower rate of sepsis than CV use (5.1% vs 15.2%; P < 0.05). Use of intravascular catheters should be balanced between the need for vascular access and the risk of sepsis.