Background relationships between income inequality and various health indicators have been the subject of much study and some controversy. We investigated associations between child mortality and income inequality amongst the wealthier OECD countries as well as changes in their relative child mortality rankings over time. Methods Data were drawn from the 2003–2006 ‘State of the World's Children’ reports published by UNICEF; Gini coefficients on income inequality were also used. Pearson correlation coefficients were calculated to investigate associations. Longitudinal child mortality data was used to compare rankings. Results We discovered very strong associations between child mortality and income inequality. In contrast to earlier results, these associations persist when the USA is excluded from the analysis. The countries with the worst child mortality figures were previously singled out in a 1993 UNICEF study on child neglect in rich nations. We also report their worsening child mortality rankings, since 1960, relative to the other OECD countries. Conclusions The results strengthen the existing evidence linking child mortality with income inequality in wealthy nations, and add to the evidence that sociopolitical factors are important in this regard.