This paper summarizes the associations between long workhours and health, special attention being given the physiological recovery and behavioral life-style mechanisms that may explain the relationship. The evidence for these mechanisms has not been systematically reviewed earlier. A total of 27 recent empirical studies met the selection criteria. They showed that long workhours are associated with adverse health as measured by several indicators (cardiovascular disease, diabetes, disability retirement, subjectivel y reported physical health, subjective fatigue). Furthermore, some evidence exists for an association between long workhours and physiological changes (cardiovascular and immunologic parameters) and changes in health-related behavior (reduced sleeping hours). Support for the physiological recovery mechanism seems stronger than support for the behavioral life-style mechanism. However, the evidence is inconclusive because many studies did not control for potential confounders. Due to the gaps in the current evidence and the methodological shortcomings of the studies in the review, further research is needed.