Long-chain (LC) polyunsaturated fatty acids (PUFA) (LCP) are considered conditionally essential nutrients for low birth weight infants (LBWI). Therefore, enrichment of LBWI formulae with metabolites both linoleic (ω-6) and α-linolenic (ω-3) acids at levels typical for human milk has been recommended. However, previous feeding trials with LCP-enriched formulae evaluated only a dietary supplementation with ω-3 LCP from fish oils alone or with both ω-3 and ω-6 LCP at levels considerably lower than usual human milk contents. We studied the effects of an LBWI formula providing the major ω-3 and ω-6 LCP, docosahexaenoic and arachidonic acids, in amounts similar to those in average human milk. Twenty-seven LBWIs were enrolled in this study when they tolerated full enteral feeding (≥ 130 ml milk/kg/day). Infants either received their own mother's milk (n = 8, birth-weight 1218 ± 146 g, gestational age 30.2 ± 1.5 weeks, mean ± SD) fortified with protein and minerals (FM-85, Nestle Ag, Munchen, Germany; dosage 5 g/100 ml milk) or were randomly assigned to blinded batches of an LBWI formula (Prematil, Milupa AG, Friedrichsdorf, Germany) without LCP (n = 10, 1280 ± 229 g, 31.1 ± 3.1 weeks) or with LCP (n = 9, 1253 ± 334 g, 30.4 ± 3.3 wks.). During the study period of 21 days, the three feeding groups did not differ in growth and feeding tolerances as assessed by occurrence of gastric residuals, spitting, or abdominal distention; however, firms stools were noted more frequently in the two formula groups. Compared to infants fed human milk, those on formula without LCP showed significant depletion of plasma phospholipid arachidonic acid (reduced to 74% of levels found in infants fed human milk) and, even more marked, of docosahexaenoic acid (reduced to 64%) as well as total LCP (74%), within 3 weeks of full enteral feeding. In contrast, infants receiving the LCP-enriched formula achieved an LCP status equal to that of human milk-fed babies. Results indicate that LBWI absorb formula LCPs and incorporate them into endogenous phospholipids. There were no adverse effects of LCP enrichment on vitamin-E status. We conclude that the LCP enrichment of the formula used in this study was well tolerated, did not interfere with short-term growth or vitamin-E status, and provided sufficient amounts of essential fatty acids to match the ω-3 and ω-6 LCP status of infants fed human milk.