A Fatigue study was undertaken to verify the existence of fluid-induced closure (FIC) in aqueous solutions for copper-nickel (70Cu-30Ni) alloy at a high loading frequency of ~100 Hz. At the near threshold region, results revealed that fatigue crack growth rates were influenced by FIC which is generally reported in the fatigue literature to be operative only in viscous liquids, not in aqueous solutions. Further support for FIC has been provided by some experimental results from the literature for other materials, such as steels, in which the effects of FIC were overlooked. A reasonable prediction of the FIC in aqueous solutions at loading frequency of ~100 Hz was made based on fundamentals of fatigue crack closure. It was estimated that as much as 25% of the applied load could be lost in aqueous solutions due to the FIC effects. The presence of FIC has significant implications on corrosion fatigue studies in aqueous solutions.