N-acetylcysteine (NAC) is used to treat Tylenol toxicity. NAC is a rich source of the sulfhydryl group (SH) which is important for replenishing the body's glutathione stores. Glutathione acts as a free radical scavenger, to decrease the damage that would be caused by those toxic radicals. Patients who undergo orthotopic liver transplantation (OLT) have a high incidence of post-operative renal dysfunction. The most common etiology of post-operative renal dysfunction is related to high levels of toxic free radicals. Free radicals may contribute to primary liver graft failure or delayed liver graft function.