The present study was conducted to clarify the structure of activities of daily living (ADL) in partially dependent older people based on interrelations among ADL items, and to examine the characteristics of ADL achievement ability (ADL ability) from the viewpoints of aging, perceptual levels of health and physical fitness, and susceptibility to disease. A questionnaire comprising 22 items representing 7 ADL domains (holding and changing the posture of the body, dressing, toilet usage, bathing, manual activity, walking, and movement and carrying) was administered to institutional therapists of 466 subjects over 60 years of age. Reliability and objectivity of each item were examined using Spearlman's order correlations, and Cohen's κ (kappa) coefficient. Factor analysis using Procrustes method was applied to determine the structure of ADL. ADL scores among groups of agestages and perceptual levels of health and physical fitness were compared using analysis of variance (ANOVA). Furthermore, in order to examine the relationship between disease and ADL ability, discriminate analysis (independent variable, ADL scores; dependent variable, susceptibility to disease) was executed. The main findings can be summarized as fo1lows. 1. Reliability and objectivity for each item were almost equal to, or higher than those of ADL scales reported previously. 2. ADL ability was classifiable into the following 7 domains: movement and carrying, dressing, standing and walking, holding and changing the body posture, manual activity, toilet usage, and bathing. 3. Although each ADL ability tended to decrease with age, this tendency was not always constant. Differences in ADL ability among age-stages were not evident for activities of low difficulty such as holding and changing the body posture and manual activity, but were evident for activities of medium to high difficulty. 4. All ADL abilities tended to be higher in persons with higher perceptual levels of health and physica1 fitness. 5. It is inferred that there are significant relationships between ADL achievement level and susceptibility to diseases such as articular impairment and cerebrovascular disorders.