BACKGROUND: Aggressiveness on the roads and/or anger behind the wheel are considered to be a major traffic safety problem in several countries. However, the psychological mechanisms of anger and/or aggression on the roads remain largely unclear. This study examines a large cohort of French employees followed over the period 1994-2001 to establish whether psychometric measures of aggression/hostility were significantly associated with an increased risk of an injury accident (I-A). An I-A was defined as a traffic accident in which someone was injured, that is required medical care. METHOD: A total of 11,754 participants aged from 39 to 54 years in 1993 were included in this study. Aggression/hostility was measured in 1993 using the French version of the Buss-Durkee Hostility Inventory (BDHI). Driving behaviors and I-A were recorded in 2001. Sociodemographic and alcohol consumption data were available from annual follow-up of the cohort. The relationship between aggression/hostility scores and I-A was assessed using negative binomial regression models with time-dependent covariates. RESULTS: The overall BDHI scoring was not statistically predictive of subsequent I-A: adjusted rate ratio (aRR) 1.02, 95% confidence interval (CI) 0.81-1.28, for participants with intermediate scores and aRR 1.25, 95% CI 0.98-1.61 for those with high scores, both compared to those with low scores. The only BDHI subscales found to be associated with I-A were 'irritability' (aRR 1.33, 95% CI 1.02-1.75 for participants with high scores) and 'negativism' (aRR 1.32, 95% CI 1.01-1.71 for participants with high scores). CONCLUSION: Overall aggression/hostility personality traits did not predict I-A in this large cohort of French employees, suggesting that aggressiveness on the roads and/or anger behind the wheel extend beyond the individual's general propensity for aggression.