Objective: To determine whether a formula containing n – 6 and n – 3 long-chain polyunsaturated fatty acids (LCP) from purified phospholipids increases the content of 20:4n – 6 and 22:6n -3 of plasma lipids and modifies the plasma antioxidant capacity in low-birth-weight infants. Study design: Seventeen infants were fed a conventional formula for low birth-weight infants (F), and 17 a formula containing n – 6 and n -3 LCP from purified pig-brain phospholipids (LCP-F). Fourteen infants receiving human milk from a human milk bank were used as a reference (HM). Growth index were measured and blood samples were taken at entry and after 15 days and 30 days of feeding. Results: In infants fed LCP-F the levels of 22:6n – 3 in total plasma lipids and in plasma phospholipids and triglycerides were higher than in infants fed F and closer to the levels of HM group throughout the study. Docosahexaenoic acid concentration in total plasma lipids was 3.46 +/- 0.19 mg/dl in infants fed LCP-F and 2.08 +/- 0.20 in infants fed F after 15 days of feeding (P < 0.001), and 3.83 +/- 0.30 and 2.15 +/- 0.20 in infants fed LCP-F and F respectively, after 30 days of feeding (P < 0.001). The concentration of 20:4n - 6 in the LCP-F was significantly higher than in the F group at 15 and 30 days of feeding. Plasma antioxidant capacity did not differ significantly between the study groups. Conclusion: Feeding low birth-weight infants a formula containing LCP phospholipids results in an increase of n - 3 and n - 6 LCP in plasma towards that of infants fed human milk. (C) 2000 Harcourt Publishers Ltd.