In recent years a major focus of attention in the field of infant nutrition has been on the role of long chain polyunsaturated fatty acids (LCPUFA) in the visual and neural development of neonates.1-8 The benefit of proposed supplementation with LCPUFA in full term infants remains controversial. Several studies have found better visual acuity in term infants fed breast milk than in formula fed infants,9-11 but others have not.6 12 There are also many potential confounders in these non-randomised studies. However, it is agreed that breastfed infants have higher concentrations of docosahexaenoic acid (DHA) in the phospholipids of the red cell membranes used as a representative marker for other cell membranes. The most pronounced effects of dietary LCPUFA supplementation have been observed in preterm infants. The visual function of infants fed a diet of either human breast milk, known to contain n-3 and n-6 essential fatty acids (EFA) or corn oil based formula feed (no dietary n-3 EFA ), has been compared in a range of different acuity tests. Both healthy preterm and full term infants were studied and it was found that at 4 months of age, visual acuity was significantly better in breastfed than in formula fed infants for both preterm and full term infants.7 9 Differences in visual acuity between the two diet regimens were most pronounced in preterm infants.9 LCPUFA from the n-3 series seem to have a selective effect on rod function with fewer effects on cone function.2 In very low birthweight infants longer term (up to 79 weeks after conception) supplementation of formula feed already containing 3–5% α-linolenic acid (n-3 EFA) and added fish oil (containing n-3 derivatives) may reduce the decline in the arachidonic (AA) and DHA content of red blood cell phospholipids3observed postnatally.13 …