The aim of this study was to assess the effects of a 7-week standardized cognitive behavioural treatment of work-related stress conducted via e-mail. A total of 342 people applied for treatment in reaction to a newspaper article. Initial screening reduced the sample to a heterogeneous (sub)clinical group of 239 participants. Participants were assigned randomly to a waiting list condition (n = 62), or to immediate treatment (n = 177). A follow-up was conducted 3 years after inception of the treatment. The outcome measures used were the Depression Anxiety Stress Scales (DASS-42) and the Emotional Exhaustion scale of the Maslach Burnout Inventory - General Survey (MBI-GS). Fifty participants (21%) dropped out. Both groups showed statistically significant improvements. Intention-to-treat analysis of covariance (ANCOVAs) revealed that participants in the treatment condition improved significantly more than those in the waiting control condition (0.001<p < or = 0.025). In the treatment group, the effects were large to moderate (0.9 (stress) > or = d > or = 0.5 (anxiety)). The between-group effects ranged from d = 0.6 (stress) to d = 0.1 (anxiety). At follow-up, the effects were more pronounced, but this result requires replication in view of high attrition at follow-up. The results warrant further research on Internet-driven standardized cognitive behavioural therapy for work-related stress. Such research should include the direct comparison of this treatment with face-to-face treatment, and should address the optimal level of therapist contact in Internet-driven treatment.