The effect of zinc deficiency on the levels of n-6 and n-3 polyunsaturated fatty acids (PUFA) in lipids from tissues of rats fed a diet containing linseed oil was investigated. Rats were fed either a control diet (25 mg Zn/kg) or a zinc-deficient diet (0.8 mg Zn/kg) for 10 d. To avoid energy and nutrient deficiency, 11.6 g of diet per day was administered by gastric tube. At the end of the experiment, rats fed the zinc-deficient diet had drastically reduced plasma zinc concentration and alkaline phosphatase activity consistent with severe zinc deficiency in these rats. Zinc-deficient rats had higher levels of n-3 PUFA, in particular eicosapentaenoic acid (EPA), and lower levels of n-6 PUFA, in particular linoleic acid, in liver and plasma phosphatidylcholine (PC) and in erythrocyte membrane total lipids than did control rats. By contrast, the levels of n-3 PUFA in PC from testes and heart, and in phosphatidylethanolamine (PE) from liver, testes and heart, were only slightly different between zinc-deficient and control rats. The study suggests that desaturation of alpha-linolenic acid is not inhibited by zinc deficiency, and that in zinc-deficient rats, n-3 PUFA preferentially incorporated into phospholipids at the expense of n-6 PUFA, especially EPA into PC. The study also shows that the effect of zinc deficiency on PUFA levels is different for PC and PE in rat tissues.