This study compares eleven countries with respect to the magnitude of mortality differences by occupational class, paying particular attention to problems with the reliability and comparability of the data that are available for different countries. Nationally representative data on mortality by occupational class among men 30-64 years at death were obtained from longitudinal and cross-sectional studies. A common social class scheme was applied to most data sets. The magnitude of mortality differences was quantified by three summary indices. Three major data problems were identified and their potential effect on inequality estimates was quantified for each country individually. For men 45-59 years, the mortality rate ratio comparing manual classes to non-manual classes was about equally large for four Nordic countries, England and Wales, Ireland, Switzerland, Italy, Spain and Portugal. Relatively large ratios were only observed for France. The same applied to men 60 64 years (data for only 5 countries, including France). For men 30-44 years, there was evidence for smaller mortality differences in Italy and larger differences in Norway, Sweden and especially Finland (no data for France and Spain). Application of other summary indices to men 45-59 years showed slightly different patterns. When the population distribution over occupational classes was taken into account, relatively small differences were observed for Switzerland, Italy and Spain. When national mortality levels were taken into account, relatively large differences were observed for Finland and Ireland. For each summary index, however, France leads the international league table. Data problems were found to have the potential to bias inequality estimates, substantially especially those for Ireland, Spain and Portugal. This study underlines the similarities rather than the dissimilarities between European countries. There is no evidence that mortality differences are smaller in countries with more egalitarian socio-economic and other policies.