The increase in life expectancy within the general population has resulted in an increasing number of elderly adults with intellectual disability, and this is reflected in the increased life expectancy in persons with Down syndrome, currently about 56 years. The aim of this study was to study the clinical characteristics, the functional status and sensori-motor function of 10 older persons with Down syndrome (mean age 59 years), 13 younger persons with Down syndrome (mean age 44 years) and compare them with 38 adults with intellectual disability without Down syndrome and a control group of people without intellectual disability. All the persons with Down syndrome and intellectual disability resided in two residential living centres in Israel, while the 31 older persons without intellectual disability (mean age 75 years), who served as the control group, lived in an independent living facility. The study considered demographic data, medical backgrounds, physical and functional tests. The results showed that the older persons with Down syndrome in the study were more obese, shorter and had more medical problems than both the older persons with intellectual disability and the control group. The functional performance of the older adults with Down syndrome was more impaired in comparison with both other groups. It is postulated that their slower responses may be explained by a less physically active lifestyle, that may accelerate the onset of disease, resulting in symptoms associated with aging that are detrimental to health. (Contains 3 tables.)