Monitoring of inequality in health has become an increasingly important task of development agencies. We compared the inequality index as published in the World Health Report 2000 with available evidence on socioeconomic inequalities in mortality in 15 industrialised and 43 less-developed countries. We found that the World Health Report index does not correspond with international variations in the size of socioeconomic inequalities in mortality. These findings indicate that the index should not be interpreted as a reflection of socioeconomic inequalities in health, nor should the index be used to replace the indices developed to monitor socioeconomic inequalities in health.