Cortical sources of resting state electroencephalographic (EEG) rhythms are abnormal in subjects with mild cognitive impairment (MCI) and in patients with Alzheimer’s disease (AD). Here, we tested the hypothesis that they reflect disease progression for future clinical trials. Resting state eyes-closed EEG data were recorded in 54 amnesic MCI subjects and in 88 mild AD patients at baseline and at 1-year follow up. LORETA was used for data analysis. In the mild AD patients, the follow-up EEG recordings showed increased power of widespread delta sources as well as decreased power of widespread alpha and posterior beta 1 sources (p<0.05). In the MCI subjects, these recordings indicated a decreased power of posterior alpha 1 and alpha 2 sources (p<0.05). Cortical sources of EEG rhythms reflect the disease progression in amnesic MCI and in AD patients. Cortical sources of resting state EEG rhythms may be used as secondary “surrogate” end points for drug discovery in prodromal and manifest AD patients.