Copper alloys are found to experience a stress relaxation during holds at maximum tension and maximum compression during cyclic loading patterns. This stress relaxation response has an effect on fatigue life by reducing the numbers of cycles to failure, particularly in the high cycle fatigue, long life regime. The stress relaxation behavior is found even for room temperature loading conditions, well below the temperature regime normally associated with creep and stress relaxation. It is suggested that the creep and stress relaxation deformation modes during hold periods is predominantly through primary creep process.