The synergistic effect of arachidonic acid (ARA) (20:4n-6) and alpha-tocopherol on the accumulation of fatty acids and the peroxidation of lipids in liver and muscle was evaluated in Atlantic salmon (Salmo salar) juveniles. Triplicate groups were fed during 12 weeks with eight experimental diets with different levels of ARA and alpha-tocopherol. In all experimental diets the productive parameters were not affected (P > 0.05). ARA accumulation in muscle and liver showed significant differences (P < 0.05) between treatments. The synergic relationship between ARA/alpha-tocopherol was influenced (P < 0.05) only in the liver, showing that high levels of alpha-tocopherol and ARA favored the fatty acids accumulation in this organ. Results indicate that a dietary concentration up to 0.6% ARA, the increment of alpha-tocopherol is not necessary. The data obtained in this study demonstrated that the interaction between the ARA and alpha-tocopherol influenced the accumulation of fatty acids in the liver