This report analysed mortality data from the World Health Organisation and income data from the annual reports of the United Nations Development Programme, sourced from 126 countries worldwide that had complete data on income inequality and mortality by age and sex around the year 2002 (including 94.4% of world human population), in order to determine whether the apparent impact of income inequality on health, which has been shown for wealthier nations, is replicated worldwide, and whether the impact varies by age. Mortality in 5-year age bands for each sex was analysed by income inequality and income level. At ages 15–29 and 25–39 years, mortality worldwide was more closely correlated with variations in income inequality than with variations in material wealth, particularly among the poorest countries in Africa. Data revealed higher mortality for a given level of overall income in more unequal nations.