This paper assesses the availability and comparability of selected indicators of inequality in health status and in health care access and use across OECD countries, focussing on disparities among socioeconomic groups. These indicators are illustrated using national or cross-national data sources to stratify populations by income, education or occupation level. In each case, people in lower socioeconomic groups tend to have a higher rate of disease, disability and death, use less preventive and specialist health services than expected on the basis of their need, and for certain goods and services may be required to pay a proportionately higher share of their income to do so. Options for future OECD work in measuring health inequalities are provided through suggesting a small set of indicators for development and inclusion in the OECD Health Data database. Some indicators appear to be more advanced for international data collection, since comparable data are already being collected in a routine fashion in most OECD countries. These include the indicators of inequalities in self-rated health, self-rated disability, the extent of public health care coverage and private health insurance coverage, and self-reported unmet medical and dental care needs. Increased availability and comparability of data will improve the validity of cross-national comparisons of socioeconomic inequalities in health status and health care access and use. Harmonisation of definitions and collection instruments, and the greater use of data linkages in order to allow disaggregation by socioeconomic status, will determine whether health inequalities can be routinely monitored across OECD countries.