This paper investigates the effect of unionization on occupational safety and health, as measured by the fatal and non-fatal work accidents, after controlling for the country's gross domestic product. It uses a panel sample of 10 European Union countries, for the period 1982-2006. The study takes into account the time persistence in work injuries and the endogenous nature of the work injuries-union density relationship. In addition, the effect of union density is decomposed into a temporary and permanent effect. It is shown that increasing union density is associated with a decrease in the number of both fatal and non-fatal work injuries.