Résumé : The aim of the Belstress Study was to see whether use of benzodiazepines is associated with perceived job stress as measured by Karasek's job-strain model. This model has as its central tenet that the most adverse health outcomes are to be expected in high strain jobs characterized by high job demands and low job control. An extension of the model states that the most noxious combination is high job demands, low control and low social support at work. Sample subjects were recruited from 25 Belgian companies between 1994 and 1998, and cover a wide range of occupations. A 5.6% of 16,094 men and 9.3% of 5012 women aged 35-59 years report use of benzodiazepines during the last month. A clear association is displayed between self-reported use of benzodiazepines and a high strain job compared to a low strain job (men: OR=1.93, 99% CI=1.4-2.6; women: OR=1.66, 99% CI=1.0-2.7), after adjustment is made for socio-demographic confounders (age, level of education, occupational group, employment sector, living situation). The independent association with quartile level of job demands is a striking feature (men: OR of highest quartile compared to lowest quartile group=1.91, 99% CI=1.4-2.6; women: OR=1.99, 99% CI=1.3-3.1). In men, an inverse association with quartile level of job control is observed (OR= 0.65, 99% CI=0.5-0.9) whereas in women a clear tendency in that direction is displayed (OR=0.62, 99% CI=0.4-1.1). The association with low social support is less clear; an independent association between use of benzodiazepines and iso-strain was observed particularly in men. © 2003 Elsevier Ltd. All rights reserved.