The interaction between creep and fatigue processes has been investigated during crack growth in sheet specimens of the aluminum alloy 5052 at 400 F. Fractographic studies indicate that at high frequencies (1 /30 Hz) the fatigue process of crack advance is dominant, whereas at low frequencies (for example, 60 Hz) the creep process prevails. It was found that at low frequencies and at a low peak stress level (10 ksi) the cyclic process could lead to an increase in the total time to failure as compared to the creep process alone.