Total parenteral nutrition (TPN) administered through a central venous catheter in low-birthweight neonates and infants has been complicated by mechanical catheter malfunctions and catheter-associated infections. A retrospective survey of catheter complications 66 infants with 90 pediatric Broviac (1.3 mm o.d.) and large-diameter (French size 3, 4, and 5) Silastic catheters revealed 17 mechanical malfunctions (27%) and 16 cases (26%) of catheter infections. The current study presents our experience using 58 small-diameter (0.635 mm o.d.) Silastic catheters for TPN in 53 neonates and infants. There were 13 episodes (22%) of mechanical problems such as accidental dislodgement, occlusion of the catheter, and perforation of the tubing. Only four cases (7%) of catheter-associated sepsis occurred, a significant reduction (p = 0.008) in this serious problem compared to the previous large catheter study. We have compared clinical features of both large- and small-diameter catheters and suggest specific guidelines for their use. The small-diameter Silastic catheter is safe, easily inserted, and effective in the critically ill, low-birthweight neonate and in young infants weighing less than 6 kg. The pediatric Broviac catheter is recommended for administration of long-term or home TPN to infants and children greater than 6 kg. These catheters are useful for multiple purposes such as blood drawing, chemotherapy, and nutritional support while the small catheter is not as versatile.