This study was designed to determine whether substituting menhaden fish oil (FO) for lard (LA) in a practical sow diet was a suitable method for enriching newborn pigs with omega-3 polyunsaturated fatty acids (n-3 PUFA). On d 107 of gestation, 18 crossbred sows were randomly allotted to one of three experimental diets, in which FO was substituted for LA at 0, 3.5, and 7% of the diet. On d 1, 7, 14, and 21 after farrowing samples of milk and serum from the sows and pig serum were collected for fatty acid analysis. The content of n-3 PUFA in the serum of sows fed FO increased six-fold over that in serum of LA-fed sows P < .0001). Feeding FO decreased the levels of arachidonic acid in maternal serum by approximately 50% (P < .0001). Similar changes were reflected in the fatty acid profiles of sow's milk. Pig serum n-3 PUFA levels were elevated over 5- and 10-fold within 24 h of birth in those litters born to sows fed 3.5 and 7% fish oil, respectively. Eicosapentaenoic acid levels in pig serum increased linearly (P < .01) during the first 2 wk postnatally in pigs suckling FO-feds sows and accounted for as much as 12% of the total fatty acids present on d 21. In conclusion, we have demonstrated that feeding FO to sows during late gestation and lactation enriches the newborn pig with n-3 PUFA.