Cognitive assessment in advanced stages of Alzheimer's disease (AD) is limited by the imprecision of most instruments. To determine objective cognitive responses in moderate and severe AD patients by way of the Severe Mini-Mental State Examination (SMMSE), and to correlate performances with Mini-Mental State Examination (MMSE) scores. Consecutive outpatients in moderate and severe stages of AD (Clinical Dementia Rating 2.0 or 3.0) were evaluated and compared according to MMSE and SMMSE scores. Overall 400 patients were included, 67.5% females, mean age 76.6±6.7 years-old. There was no significant impact of age or gender over MMSE or SMMSE scores. Mean schooling was 4.4±2.5 years, impacting SMMSE scores (p=0.008). Scores on MMSE and SMMSE were significantly correlated (F-ratio=690.6325, p<0.0001). The SMMSE is influenced by schooling, but not by age or gender, and is an accurate test for assessment of moderate and severe AD.