Sex hormones may influence the enzymatic synthesis of long-chain polyunsaturated fatty acids (LC-PUFAs), which may lead to sex-specific differences in LC-PUFA status. Isotope studies with U-(13)C α-linolenic acid (ALA) have shown a considerably higher conversion rate of ALA to n-3 (omega-3) LC-PUFAs in women than in men. A review of the literature generally suggested that there was a higher contribution of arachidonic acid (AA) and docosahexaenoic acid (DHA) in blood lipids in women than in men; however, sex-specific differences were not seen in every study. The fatty acid composition of plasma phospholipids was recently reported separately for a large group of women and men (n > 3000) living in 15 regions of Europe. The contributions of saturated and monounsaturated fatty acids were higher, whereas those of AA and DHA were lower in men than in women; however, sex explained only ≈ 2% of the variability of plasma phospholipid DHA values. Results reported from a limited number of randomized controlled trials of perinatal LC-PUFA supplementation have, on occasion, shown sex-specific differences in some outcomes; however, the heterogeneity both in the interventions and outcomes measured made it difficult to draw conclusions on the direction or the extent of the effects. Data summarized in the current review highlight the importance of planning a subgroup analysis by sex in perinatal LC-PUFA supplementation trials.