BACKGROUND: The aim of the study was to assess overall and cause-specific mortality among employees and former employees of the main public transport company in the Paris region. METHODS: The cohort included all personnel employed between 1980 and 2012 with at least 1 year of service. Vital status and causes of death were obtained from national registries and classified according to the European shortlist for causes of death. Occupations were categorized into 22 distinct groups, and complete occupational histories were reconstructed. Cox proportional hazards models were used to estimate survival by socio-professional group and hazard ratios of death by occupation. Standardized mortality ratios (SMRs) were calculated to compare mortality with that of the general population of the Paris region. RESULTS: A total of 96,634 individuals (78,702 men and 17,932 women) were included. By the end of follow-up, 14.6% of men and 6.5% of women had died. A social gradient in survival was observed with marked differences in the hazard ratios of mortality across occupational categories. Among men, significant excess mortality was found for kidney cancer (SMR = 1.24), acute myocardial infarction (SMR = 1.17), chronic liver disease (SMR = 1.11), and suicide (SMR = 1.20). Among women, mortality due to transport accidents was significantly in excess (SMR = 1.85). Specific excesses were found by occupation: for example, in men, tumors in skilled maintenance workers (SMR = 1.67), ischemic heart disease in bus drivers (SMR = 1.21), security staff (SMR = 2.02), and unskilled workers (SMR = 1.18), and in women, cerebrovascular diseases in bus drivers (SMR = 1.85). CONCLUSION: These findings highlight occupational inequalities in mortality and support strengthening targeted prevention strategies for high-risk workgroups.