Objective: To examine the bidirectional relationship between job strain and cynicism. Methods: The study sample was obtained from the Young Finns study and comprised 757 participants (399 women, 53%). The bidirectional association between cynicism and job strain over a 6-year-follow-up was examined with a cross-lagged structural equation model, controlling for a number of demographic variables. Results: High job strain (beta = 0.08; P = 0.007) was associated with higher baseline-adjusted cynicism 6 years later. Nevertheless, cynicism was not associated with baseline-adjusted job strain. The additional analysis showed that cynicism mediated 21.5% of the relationship between job strain and depression. Conclusions: Perceptions of having a highly strenuous job may elicit mistrustful and cynical attitudes in employees, which in turn may lead to mental health problems.