1. 1. The benefit of dietary vitamin E supplementation in preventing oxidative-induced lung injury was investigated. Three day preterm guinea pig pups were exposed to hyperoxic (85% O 2) or normoxic (21% O 2) conditions. The animals were fed either a standard low birthweight human infant formula milk (6.4 mg/l vitamin E), or a vitamin E supplemented milk (100 mg/l) for up to 7 days. 2. 2. After 3 days vitamin E supplementation, plasma but not erythrocyte vitamin E concentrations were elevated, while following 7 days both plasma and erythrocyte vitamin E concentrations were significantly increased. 3. 3. Lung and liver vitamin E concentrations were elevated at both 3 and 7 days. At 3 days the increase in lung vitamin E was oxygen-dependent, suggesting that the lung increases uptake of vitamin E in response to oxidative stress. 4. 4. Despite an increase in the vitamin E concentration of the lungs of preterm guinea pigs, no amelioration of the lung injury was observed. These results suggest that although vitamin E is a potent antioxidant, it is unable to protect adequately the lungs from reactive oxygen species in the absence of sufficient primary enzymatic antioxidant defences.