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The rotating bending high cycle and the push-pull low cycle fatigue tests were performed on the cold-worked Al-2.4% Mg alloy, and its fatigue properties were examined and compared with those of the solution-treated one reported previously in another paper.The cold-worked Al-2.4% Mg alloy did not show the cyclic softening during cyclic straining. This fact might be closely associated with the strong dynamic strain ageing property of the present material.The cyclic stress-strain relation was not influenced by the amount of the reduction given to the material.The cold-work reduced the low cycle fatigue life of the solution-treated alloy, but it did not depend on the reduction ratio, as in the cyclic stress-strain relation. On the other hand, the exponent, slip is concentrated at and near the grain boundary in the former, while it is uniformly dispersed, independent of grain boundary, in the latter. The effect of the cold-work on the high cycle fatigue strength of the Al-2.4% Mg alloy was very small, compared with those of other metal materials. This might be due to the small inclusions contained in the material, from which fatigue crack originates.