For the majority of correctional officers, working in a prison constitutes a unique work environment, with specific occupational hazards (stress, feelings of insecurity, etc.). In this cohort study, the French Institute for Public Health Surveillance analyzed the causes of death among individuals who served as prison officers between 1990 and 2008, totaling more than 40,000 people. Their all-cause and cause-specific mortality was compared to that of the general French population over the same period using age- and year-standardized mortality ratios (SMR). The 1,754 deaths observed between 1990 and 2008 represent the lower-than-average all-cause mortality typically observed in worker cohorts. However, a statistically significant excess of suicide (+21%) was observed among men. This finding was observed between 1990 and 2008, with no worsening or improvement over time. The excess specifically concerns the occupations of prison guard and technical assistant. No positive association was observed between the occupational indicators studied (type of facility, prison occupancy rate) and the risk of suicide. This excess suicide rate is consistent with data from the literature. Although the available data do not allow us to determine the extent to which occupational factors may have contributed to suicide among prison staff, the results reinforce the importance of continuing prevention measures, epidemiological monitoring, and studies in this population to better understand the causes of this excess mortality by suicide.