Parenteral nutrition via central venous catheterization is associated with serious risks, especially that of sepsis. Lipid emulsion (Intralipid[Sweden]), which may be administered peripherally, was evaluated for its potential to support microbial growth. Washed cultures of Staphylococcus aureus, Candida albicans, and three species of Gram-negative rods were all capable of multiplying in the emulsion at room temperature. Variations in inoculum size did not affect the growth rate. Studies comparing the emulsion to amino acid-glucose solutions (total parenteral nutrition [TPN])confirmed other reports that TPN inhibits the growth of certain bacteria but merely retards fungal multiplication. When human serum was added to the lipid emulsion in an attempt to simulate in vivo conditions at the catheter tip, Escherichia coli was inhibited while the growth of S aureus and C albicians was unaltered.