A translated version of the Mattis Dementia Rating Scale (DRS) into Greek ((DRS-GR) was applied to a sample of Greek population (N = 356) comprising normal middle-aged and elderly subjects (controls), as well as patients suffering from Parkinson's (PD) and Alzheimer's disease (AD) to test its reliability and validity. A well-known dementia screening instrument, the Mini Mental State Examination test (MMSE), and a nonverbal measure of abstract reasoning, the Raven Coloured Progressive Matrices, were employed as measures of DRS-GR concurrent validity. Reliability analysis was satisfactory with Cronbach's alpha reaching 0.82 and item to total correlations yielding high coefficients for most items. DRS-GR scores were influenced by age and education, but not by gender. Correlation between MMSE and the total DRS-GR score was significant in patients and normal controls, but correlation between DRS-GR and RCPM was significant in AD and nondemented PD only. Specificity and sensitivity for dementia screening, calculated on a Receiver Operating Characteristic curve, with a cut-off score the mean value minus two standard deviations, corrected for age and education, was 96% and 80%, respectively. Our preliminary findings show that DRS-GR is a reliable and well-adapted instrument for clinical application in the Greek population.