An increase in social inequalities in premature mortality has been observed in the last decades in various European countries. In France, large inequalities have been reported for several years, but the changes over time have been only partially examined. The study was based on the analysis of a large longitudinal data set. Four periods of 7 years following a census were compared. Deaths in the period (21,003 deaths for men, 9,418 for women) were recorded and studied according to socioeconomic status (SES) at the census. Relative Index of Inequality (RII) was calculated in order to quantify the magnitude of inequalities among those employed, and also in the entire population, with specific categories for those inactive. The results showed that the magnitude of inequalities remained mainly stable over time for men and women working at the time of the census. However, for the entire population, a strong increase in the magnitude of social inequalities was observed. For men the RIIs increased from 3.53 in the first period to 6.54 in the most recent period. For women, the corresponding figures were 1.94 and 3.88. The increase was observed also for specific causes of deaths: cancer and cardiovascular diseases for both sexes, and external causes for men. In spite of a global decrease in the mortality over the period, the absolute differences between the top and the bottom of the socioeconomic scale did not change. The results highlight the importance of temporal changes in mortality associated with an increase of unemployment, changes in the labour market, and the consequences of selective exclusion from work. The classification of those not working is an important point to consider in the study of social inequalities.