The aim of this study was to prospectively investigate the effect of potential workplace closure, an externally attributed form of job insecurity, on fatigue and psychological distress. In April 1999, the minister responsible announced that a governmental agency would close down one of its two locations. Baseline data from the employees were available before the closure announcement (n = 574) because they were enrolled in the Maastricht Cohort Study on "Fatigue at Work." In the closure group, the relative risk for becoming a psychological distress case was 1.61 (95% confidence interval [CI] = 1.27-2.05) during 13 months after the closure threat. Within the closure group, a difference in relative risk for psychological distress was observed between employees who self reported an increase in job insecurity (relative risk = 1.85; 95% CI = 1.41-2.42) and employees who did not report an increase in job insecurity (relative risk 1.14; 95% CI = 0.58-2.24)