In order to investigate the effect of an increasing linoleic acid content of the diet on vitamin E requirement, young male rats were divided into 4 groups receiving respectively 0.27, 0.98, 3.57 and 12.98% linoleic acid (from mixtures of coconut oil and tocopherol-free safflower oil) in their diets. Each group was subdivided into 6 groups, receiving increasing amounts of D-α-tocopheryl acetate (2.5–23.5 mg) in their food. Spontaneous haemolysis in vitro was used as a criterion for vitamin E requirement. The amount of D-α-tocopheryl acetate needed to prevent haemolysis was 13 mg/kg food for the lowest three doses linoleic acid, the highest dose required 18 mg/kg food. The fatty acid composition of erythrocyte lipids was not influenced by the vitamin E content and only moderately by the linoleic acid content of the diet: a higher level of dietary linoleic acid caused an increase in linoleic acid content of erythrocyte lipids, which was mainly compensated by a decrease in oleic acid content. The group with the lowest dose of vitamin E and the highest dose of linoleic acid showed a significant increase in non-electrolyte (= thiourea) haemolysis t