A brief (ten-minute), easily administered battery of four psychological tests was developed to classify successfully 98% of patients with mild dementia of the Alzheimer's type and healthy older persons matched for age, sex, and social position. Only two of 84 persons (one demented, one healthy) were misclassified. The four tests are the logical memory and mental control subtests of the Wechsler Memory Scale, Form A of the Trailmaking Test, and word fluency for letters S and P.