Patients with amnesic Mild Cognitive Impairment (aMCI) are considered to be in a prodromal state of Alzheimer's Disease (AD), and show an increased risk of progression to AD dementia. Both β - amyloid deposition and Tau hyperphosphorylation are involved in the pathogenesis of AD, and may lead to synapse loss and neuronal death. Cortical Thickness measurements from Magnetic Resonance Imaging (CT-MRI) can detect cortical thinning and regional atrophy in these conditions. Objective: To compare regional brain differences in CT-MRI in patients with aMCI of degenerative etiology and AD dementia. The study population included 10 aMCI patients (5 female patients; age: (median ± SD) 78,50 ± 3,53 years; education: (median ± SD) 11,40 ± 4,00 years; Mini Mental State Examination (MMSE) score: (median ± SD) 27,60 ± 1,07), and 14 AD dementia patients (8 female patients; age: 76,29 ± 8,74 years; education: 11,79 ± 4,74 years; MMSE: 20,21 ± 6,79), right-handed, matched for age and level of education. Cortical thickness (CT) was measured with FreeSurfer, and differences in patterns of reduced CT in the different patient groups were assessed using one-way ANOVA. Significant differences in CT measurements were found at different regions of interest and amongst the different patient groups. Compared to aMCI patients, patients with AD dementia showed cortical thinning at the posterior dorsal area of the cingulate gyrus (left) (F:5,866;p:,024); medial occipitotemporal sulcus (collateral sulcus), and lingual sulcus (left) (F:4,564; p,044); inferior precentral sulcus (left) (F:7,279; p:,013); inferior temporal sulcus (left) (F:7,769; p:,011); posterior transverse collateral sulcus (right) (F:4,288; p:,050); pericallosal sulcus (right) (F:6,411; p:,019), and inferior temporal sulcus (right) (F:5,727; p:,026). Patients with AD dementia showed cortical thinning at several cortical regions usually involved in the pathogenesis of AD. CT measurements may represent an inexpensive and widely available biomarker of cortical damage, useful in early diagnosis of AD as well as of other degenerative dementias.