OBJECTIVE: The effects of work-related stress are generally judged to be detrimental to workers' health and costly for society. The purpose of this study is to set out an evaluation of the costs of work-related stress for France. METHODS: Occupational stress is defined according to Karasek and Theorell's model. Illnesses included in the study are cardiovascular diseases, depression, musculoskeletal diseases and lower back pain. The model resorts to the principle of attributable fractions, which is based on two parameters, 1) prevalence of exposure to occupational stress, (2) relative risk to develop an illness as a consequence of occupational stress. The valuation of these two parameters is based on a systematic review of scientific literature (epidemiological studies). Cost estimates include medical costs, cost of absence from work, loss of potential output because of years of activity lost before retirement age and a valuation of years of life lost attributable to occupational stress (per capita GDP). Cost estimates are based on national statistical reports and reported in 2000 Euros (€). RESULTS: The sensitivity analysis shows that from 220,500 to nearly 335 000 persons (from 1% to 1.4% of working population) were affected by illnesses attributable to work-related stress and from 1600 to nearly 3000 people died as a result of their illness. As for the diseases considered here, work-related stress costs society from 830€ million to 1656€ million in France, which represents from 0.06% to 0.12% of GDP, and from 10.3% to 20.5% of the total spending of social security work injuries branch. CONCLUSIONS: These results reflect a certain proportion of total economic and human burden of occupational stress. The study underlines the necessity of convergent epidemiological studies capable of determining as reliably as possible the value of relative risk for the illnesses.