Fatty acid composition was evaluated on sow milk and on different piglet tissues at days 0, 7, 14, 21 and 28. The postnatal evolution of delta5 (D5D ) and delta6 (D6D) desaturase mRNA expression was also measured in the liver of low 18: 3 n - 3 and high 18:3n -3 piglets. The milk of high 18:3n-3 sows had higher proportions of n-3P UFA than that of low 18:3n-3 and medium 18:3n -3 sows.