Comparison of lipid damage during frozen storage and the capacity of the natural antioxidant to retard oxidation of polyunsaturated fatty acids in swordfish muscle were investigated. Swordfish fillets were packaged in low density polyethylene with or without the natural antioxidant and frozen for 12 months at −20℃. In the twelfth month, swordfish packed with natural antioxidant showed a lower lipid hydrolysis than in swordfish control sample. Furthermore, swordfish packed with natural antioxidant showed a lower lipid oxidation (primary and secondary lipid oxidation) than in muscle of swordfish control sample. In fact, the total oxidation observed was lower in the samples packed with natural antioxidant than the control during the frozen storage. The results confirm the efficacy of an active packaging with a natural antioxidant derived from barley husks to slow down the progress of lipid hydrolysis and increase oxidative stability in swordfish muscle.