The effects of environment on fatigue behavior are quite intimately related to such test variables as stress intensity, cyclic frequency, and temperature. The effect of these variables has been shown to be quite complex. However, a consistent pattern of behavior is beginning to emerge which, it is hoped, will lead to a considerably changed understanding of the corrosion-fatigue process. It is considered probable that an increased understanding of the corrosion-fatigue process will also contribute measureably to an improved understanding of general fatigue processes. Material variables such as composition, directionality of properties, and microstructure, have important effects on corrosion-fatigue behavior of aluminum alloys. However, it appears that these variables, at least in gaseous environments, may be important largely because of their effects on the mechanical behavior of aluminum alloys. On the other hand, studies in seawater suggest that these variables become increasingly important as the corrosive nature of the environment increases. This memorandum discusses in detail the effects of both test variables and material variables on corrosion fatigue. In addition, current theories of corrosion-fatigue mechanisms are outlined, and several methods of preventing corrosion fatigue are suggested. (Author).