Contrast-induced acute kidney injury (CI-AKI) accounts for approximately 10% of all causes of hospital-acquired renal failure, causes a prolonged in-hospital stay, and represents a powerful predictor of poor early and late outcome. N-acetylcysteine (NAC) is a thiol compound classically known as a mucolytic agent, which is a potent antioxidant that scavenges a wide variety of oxygen-derived-free-radicals and may be capable of preventing acute kidney injury. In the present study, we will review (1) the pathophysiology of the CI-AKI and (2) the experimental and clinical data on the effects of NAC in preventing CI-AKI.