Plasma AlphaBeta levels have been examined in sporadic Alzheimer's disease yielding conflicting results; both no difference and an increase in plasma concentrations of A1-42 and A1-40 in sporadic cases of AD as compared to controls have been reported. Elevated plasma A1-42 levels may be detected several years before the onset of symptoms (in mild cognitive impairment stadium). Levels of AlphaBeta140 and AlphaBeta142 were measured in plasma from 54 patients with AD, 39 subjects with MCI and 35 controls using a commercially available ELISA. Mean plasma AlphaBeta142 levels were significantly higher in MCI as compared to both AD (P<0.001) and control subjects (P<0.001), while AlphaBeta140 did not differ between the groups. No correlations were observed between A levels and age, MMSE scores or gender. According to ROC curve analysis the maximum accuracy in discriminating MCI versus both controls and AD subjects has been achieved using a cut-off value of 3.8.