It has been suggested for many years that inclusion of fishmeal in diets for breeding sows gives improved reproductive performance, but there have been few experiments to objectively measure the effects of fishmeal inclusion. Recently, attention has focussed in many species on the possible beneficial effects of the long chain omega-3 fatty acids contained in fish oil on a number of aspects of reproduction, including embryo survival, gestation length, fetal growth and neonatal viability. This experiment was therefore carried out to measure the effect of feeding diets with or without inclusion of fishmeal with a high content of omega-3 fatty acids on sow reproductive performance.