Revised Hasegawa's dementia scale (HDS-R), consisting of 9 simple questions with a maximum score of 30, was examined in its usefulness for screening age-associated dementia in a total of 157 subijects: 95 demented patients and 62 non-demented persons. The two groups were age-matched. Cronbach's coefficient alpha was as high as 0.90 in HDS-R. In addition, the coefficient of correlation of each question's score to the total score of other questions in the IHDS-R was significantly high, ranging between 0.79 and 0.40. These findings proved that the HDS-R could satisfy the fundamental prerequisite for dementia screening tests: reliability in terms of internal consistency. Clinical applicability of the HDS-R was confirmed by the following two findings. (a) significant differences were noted between the demented and non-demented groups in each question's score, total mean score and mean score by DS-based severity. (b) Dementia could be most exactly discriminated from non-dementia with sensitivity of 0.90 and specificity of 0.82 at a cutoff point of 20/21 . The coefficient of correlation of the HDS-R to the MMSE was as high as 0.94, proving the HDS-R to be valid in terms of compatability with the established dementia screening test. In conclusion, the HDS-R can screen dementia at the highest conceivable accuracy and efficiency. It may also serve to assess the severity of dementia changing with time and the effect of pharmacotherapy and rehabilitation. Keywords: dementia, screening test, HDS-R, sensitivity, specificity INTRODUCTION Since the primary symptoms of dementia are cognitive decline, various intelligence tests such as the WAIS (Weschesler Adult Intelligence Scale) have f used for its assesment. However the WAIS is not generally able for screening for dementia since it takes too long to administer, and has not been adequately standardize for elderly subject with cognitive changes associated with normal aging. For the purpose of screening for dementia, questions dimild be eat answered key normal elderly persons, bu...