We estimated disability prevalence among adults at global, regional and country levels using internationally comparable disability data and measure. We conducted a retrospective analysis of data from the World Health Survey (WHS) (2002-2004) for nationally representative samples of civilian, non-institutionalized populations in 54 countries. A disability was measured as having at least one severe or extreme difficulty with bodily functions (seeing, concentrating) and activities (moving around, self-care) based on an individual's self-reports. In the 54 countries under study, severe or extreme functional or activity difficulties are highly prevalent. For all countries, disability prevalence is estimated at 14% for all adults. Low and middle income countries have higher disability prevalence compared to high income countries. Among subgroups, disability prevalence stands at 12% among working age adults and 39% among the elderly. Women have higher prevalence than men. Disability is found to be highly prevalent among adults, with an estimated global prevalence at 14%. Disability deserves enhanced policy attention and resources in public health and international development.