In a population survey aimed to detect cases of Alzheimer's disease and other dementias, two preliminary diagnoses were made independently with the purpose of using the concordant diagnoses as final diagnoses. Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition, diagnostic criteria were followed. The 668 subjects examined were selected from the population of an area in Stockholm, Sweden, aged 75 years or more, with the Mini-Mental State Examination used as a screening test. The agreement on dementia diagnosis was moderate (kappa = .54) and could be clearly improved (kappa = .70) with modifications to the diagnostic criteria, such as adding a category of questionable dementia and giving more guidelines in the definition of impairment of a function. The agreement on the diagnosis of Alzheimer's disease vs vascular dementia vs secondary dementia was substantial (kappa = .67) when the cases with concordant dementia diagnoses were examined.