The aim of this study was to determine the diagnostic value and agreement analyses between Clinical Dementia Rating (CDR) and dementia diagnostic criteria (gold standard), Blessed Dementia Rating scale (BDRS), and Diagnostic and Statistical Manual of Mental Disorders, 3rd Edition, Revised (DSM III-R) criteria for severity. In a sample of 343 Southern Brazilian participants, CDR was consecutively assessed in 295 dementia patients (Alzheimer disease, vascular dementia, and questionable) and 48 healthy elderly. The National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria for probable Alzheimer disease and the National Institute of Neurological Disorders and Stroke and Association Internationale pour la Recherché et l'Enseignement en Neurosciences (NINDS-AIREN) for probable vascular dementia were the gold standard. A battery of cognitive tests and the Mini Mental State Examination (as a screening test at study entry) were also applied. Sensitivity and specificity were obtained through contingency tables. Validity and reliability were measured through kappa coefficient, Kendall b, and percent agreement. CDR agreement among raters was demonstrated by percent agreement. Agreement to gold standard was good (kappa=0.75), as well as to the Blessed scale (kappa=0.73), and excellent to the DSM III-R (kappa=0.78). CDR detection of dementia among healthy elderly or questionable dementia was 86% and 80% sensitive, respectively, and 100% specific for both settings. In conclusion, agreement of CDR global score with the gold standard was good, and diagnostic values were high.