Summary The limited amount of fish oils available has resulted in an increased use of vegetable oils in the feed for farmed fish, such as Atlantic salmon. The aim of this study was to evaluate how this has affected the fatty acid (FA) composition of farmed Atlantic salmon and to compare the FA composition of 20 farmed Atlantic salmon with that of 20 wild Atlantic salmon caught in the sea. Fillet fat of farmed salmon was about 12%, which is twice that found in wild salmon. The FA composition of the farmed salmon confirmed a substantial inclusion of vegetable oils in the feed, but the total amount of long chain n‐3 FA present in the fillets of farmed salmon was higher than in the wild fish. A standard portion of farmed Atlantic salmon fillet (200 g) provides approximately 2 g of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which is four times higher than the minimum daily intakes recommended by the UK's Scientific Advisory Committee on Nutrition and the World Health Organisation.