The Mini-Mental State Examination (MMSE) has not been validated in the Lebanese population and no normative data exist at the national level.To evaluate the reliability and validity of an Arabic version of MMSE developed by the "Groupe de Travail sur les Démences de l'Université Saint Joseph" (A-MMSE(GTD-USJ)) and to provide normative data by gender, age, and education in adults over 55.Study design: national cross-sectional survey.1,010 literate community-dwelling Lebanese residents aged 55 and above.reproducibility, internal consistency, sensitivity, specificity, predictive values, and area under the curve of the A-MMSE(GTD-USJ) for the detection of cognitive impairment using the Clinical Dementia Rating (CDR) as the gold standard. Normative data were established from 720 healthy adults. A-MMSE(GTD-USJ) scores corresponding to the 5th, 10th, 15th, and 50th percentiles were identified according to gender, age, and education.Intra-rater and inter-rater test-retest score correlations were 0.89 and 0.72, respectively. Cronbach alpha coefficient for internal consistency of the A-MMSE(GTD-USJ) was 0.71. A threshold value of 23 provided a sensitivity of 80% and a specificity of 89.4%. The area under the curve was 0.92. A-MMSE(GTD-USJ) scores increased with education and decreased with age. Women had significantly lower scores than men. Normative data for A-MMSE(GTD-USJ) stratified by gender, age, and education were generated.In reference to the CDR, the A-MMSE(GTD-USJ) is a valid tool to assess cognitive status among Lebanese subjects aged 55 and above. Normative data will help clinicians in detecting cognitive impairment in this population.