The early diagnosis of Alzheimer's disease (AD) remains difficult to make. In order to better specify the advantage of assaying the amyloid beta peptide (Aβ1-42) and the total tau protein (t-tau) in this pathology, we studied three rigorously selected and age-matched populations: control (C) ( n = 32), patients with AD (n = 87) or another neurodegenerative disease (Mn) (n = 31). The combination of the Aβ1-42 peptide and the t-tau protein offers a sensitivity of 85.29% for AD and a specificity of 96.77% to differentiate the controls. Thus the combination of these two markers helps in the diagnosis of AD thanks to the great specificity and sensitivity of this method.