BACKGROUND: the major purpose of health and social policy in old age is to increase quality of life of elderly people. In many demographically developing countries, life expectancy is increasing very rapidly, but little information is available on survival free of disability. OBJECTIVES: to determine prevalence and severity of disability among the elderly population and to compare disability-free life expectancy and self-care life expectancy among different age groups and between men and women. DESIGN: a cross-sectional multi-stage random sample survey and routine life tables for Thailand. SETTING: national population of Thailand. SUBJECTS: 4,048 elderly subjects aged 60+ years. RESULTS: prevalence rates (95% CI) of long-term disability and dependency in self-care activities of daily living were 19% (95% CI 17.8, 20.2) and 6.9% (6.1, 7.7) respectively. Rates of disabilities increased with age and women were more disabled than men. The life expectancy and disability-free life expectancy at age 60 for men were 20.3 years and 16.4 years, and for women were 23.9 years and 18.2 years respectively. Self-care life expectancies at age 60, calculated from the prevalence of needing help with basic self-care activities, were 18.6 years and 21.3 years for men and women respectively. Women spent proportionately more of their longer life expectancy in a disabled state than men. Men and women can, respectively, expect that 19% and 24% of their life expectancy at age 60 will be spent in a disabled state, but may expect only about 10% of their life expectancy to be spent unable to manage basic self-care activities of daily living. CONCLUSION: long-term disability is common in old age, affecting a quarter of people over 60 years. However, self-care problems are much less common and suggest that the social and health care consequences of demographic transitions are over-estimated by use of simple questions about limiting long-standing disability. Self-care life expectancy provides a useful monitoring tool for censuses and national disability surveys.