The antioxidant activity of resveratrol (1) and several acylated and glycosylated derivatives on fish oil enriched systems has been studied. Two long-chain acylated derivatives, 3-stearoylresveratrol (2) and 4'-stearoylresveratrol (3), and three glucosyl derivatives, resveratrol-3-beta-d-glucopyranoside (piceid, 4), resveratrol-3,5-di-beta-d-glucopyranoside (5), and resveratrol-3,4'-di-beta-d-glucopyranoside (6), have been prepared and tested. The results have shown a notable antioxidant capacity of resveratrol and piceid in fish oil-in-water emulsions, similar to that of the potent antioxidant hydroxytyrosol. Lipophilization of resveratrol did not improve its antioxidant activity, either in emulsions or in bulk fish oil. Further glucosylation of piceid yielding compounds 5 and 6 did not improve either resveratrol or piceid antioxidant efficiency in emulsions or in bulk oil. In all of the examples, the hydroxyl group at the 4'-position seems to be relevant for the antioxidant efficiency of resveratrol, and it should be maintained to keep the antiradical activity. Finally, resveratrol has shown to be a very good antioxidant for fish muscle, as good as the potent antioxidant hydroxytyrosol.