Lipid emulsions for parenteral use are peroxidized during storage, indicating that the amount of the natural vitamin E in the preparations is inadequate. Peroxidation products in the lipid emulsion preparations can induce cell damage in vitro. The parenteral administration of lipid emulsions increases in vivo lipid peroxidation in adult and healthy newborn patients as well as in premature infants, whereas enteral feeding seems to lead to a more balanced accretion of polyunsaturated fatty acids. The use of parenteral lipids has recently been associated with increased morbidity of premature infants. Current opinion favors the view that evolution of the complications is highly influenced by the inferior defense of the premature infants to resist oxidant loads. A novel antioxidant added in the preparations for the intravenous provision of polyunsaturated lipids could be beneficial for such patients.