Oxidative stress is a key factor involved in the development and progression of Alzheimer's disease, and it is well documented that free radical oxidative damage, particularly of neuronal lipids, proteins, nucleic acids and sugars, is extensive in brains of Alzheimer's disease patients. However, oxidative stress may elicit compensatory responses and downstream adaptations such as amyloid-beta deposition and neurofibrillary tangle formation, which may function as "shields" to ensure that neuronal cells do not succumb to oxidative injuries. Although during the past several years our understanding of the mechanisms leading to neuronal damage and death in the course of Alzheimer's disease has improved significantly, we have not found an effective therapeutic to fight this devastating disorder. However, the results obtained in clinical trials with antioxidants are promising and propel us in the search of new and more effective antioxidant therapies.