We describe here the methods used to produce the first estimates of healthy life expectancy (DALE) for 191 countries in 1999. These were based on estimates of the incidence, prevalence, and disability distributions for 109 disease and injury causes by age group, sex, and region of the world, and an analysis of 60 representative health surveys across the world. We used Sullivan's method to compute healthy life expectancy for men and women in each WHO member country. Japan had the highest average healthy life expectancy of 74.5 years at birth in 1999. The bottom ten countries are all in sub-Saharan Africa, where the HIV-AIDS epidemic is most prevalent, resulting in DALE at birth of less than 35 years. Years of healthy life lost due to disability represent 18% of total life expectancy in the bottom countries, and decreases to around 8% in the countries with the highest healthy life expectancies. Globally, the male-female gap is lower for DALE than for total life expectancy. Healthy life expectancy increases across countries at a faster rate than total life expectancy, suggesting that reductions in mortality are accompanied by reductions in disability. Although women live longer, they spend a greater amount of time with disability. As average levels of health expenditure per capita increase, healthy life expectancy increases at a greater rate than total life expectancy.