In order to evaluate the effect of vegetable oils on gilthead seabream health, fish were fed different diets formulated substituting 60 per cent of fish oil by soybean oil (60SO), rapeseed oil (60RO) or linseed oil (60LO). 80 per cent of fish oil substitution by either soybean oil (80SO) or linseed oil (80LO) plus a mix of vegetable oils at 60 percent substitution were also assayed. A 100 percent fish oil diet (FO) was used as a control diet. After 7 months of feeding, basal levels of different immunological parameters were determined. Besides, response to a confinement stress and fatty acid composition of liver and head kidney macrophages was studied. The inclusion of soybean oil decreased ACH50 and head kidney phagocytic activity. Rapeseed oil decreased phagocytic activity. Linseed altered stress response. Soybean oil produced steatosis in liver hepatocytes. A selective incorporation of some EFAs such as DHA and ARA was observed.