Results from a French case-control study of acute leukaemia and occupational exposure for the risk associated with exposure to electromagnetic fields (EMF) are reported. There were 185 cases and 513 controls. A significantly increased risk of acute leukaemia was observed for exposure to EMF other than that from arc welding (odds ratio = 4.04, 95% CI 1.26-12.88) which persisted after adjustment for possible confounding exposures. This study supports the hypothesis that workers exposed to some EMF have an increased risk of leukaemia.