Introduction: Disease modifying treatment strategies for Alzheimer’s disease (AD) have led to a severe need for finding biomarkers to be able to establish a reliable diagnosis at a very early stage and also to follow up the patient and their response to therapy. Amyloids β (Αβ) which predominate in amyloid plaques constitute one major neuropathologic hallmark in AD, are produced by all types of cells in the central nervous system and almost all cells in peripheral tissues. Increased plasma level of this peptide is reported in prodromal stage of AD, in mild cognitive impairment. Conclusion: Different genetic, imaging and biochemical studies suggest that increased plasma Aβ can begin many years before the onset of symptoms in AD, indicating that it does not require preexisting neural abnormalities. It remains to be verified if the proof of plasma Aβ in clinically healthy subjects represents a prognostic factor pointing to a risk of pending AD.