Most of the empirical evidence regarding the impact of reductions of standard working hours analyzes its effects on employment outcomes, family life balance, and social networks, but there is no empirical evidence of its effects on health outcomes. This study uses panel data for France and Portugal and exploits the exogenous variation of working hours coming from labor regulation and estimates its impact on health outcomes (from 39 to 35 hours a week and from 44 to 40 hours a week, respectively). Results suggest that the mandatory reduction of standard working hours decreased the working hours of treated individuals (and not the hours of individuals in the control group). Results also suggest that the fact of being treated generated a negative (positive) effect on young males’ (females’) health in France. No effects on health outcomes were found for Portugal.