In the interesting debate entitled "Challenging Views of Alzheimer's Disease II," we defended the position that factors such as oxygen, the single methionine residue of amyloid beta-peptide(1-42) [Abeta(1-42)], and redox metal ions were important for the oxidative stress and neurotoxic properties of this peptide that is critically involved in the pathogenesis of Alzheimer's disease. This brief review summarizes some of our findings relevant to the role of the single methionine residue of Abeta(1-42) in the oxidative stress and neurotoxic properties of this peptide.