BACKGROUND: Cognitive behaviour therapy (CBT) for chronic fatigue syndrome (CFS) is an effective but intensive treatment, requiring trained therapists. A minimal intervention based on CBT for CFS, guided self-instruction, was shown to be an effective treatment when delivered in a tertiary treatment centre. Implementing this intervention in a community-based mental health centre (MHC) will increase the treatment capacity for CFS patients. This study evaluated the effectiveness of guided self-instruction for CFS implemented in an MHC, delivered by nurses. Method One hundred and twenty-three patients were randomly assigned to either guided self-instruction (n=62) or a waiting list (n=61). Randomization was computer generated, with allocation by numbered sealed envelopes. Group allocation was open to all those involved. Patients fulfilled US Centers for Disease Control and Prevention (CDC) criteria for CFS. Primary outcome variables were fatigue severity and physical and social functioning, measured with the Checklist Individual Strength (CIS) and the Medical Outcomes Survey Short Form-36 (SF-36) respectively. RESULTS: After 6 months, patients who followed guided self-instruction reported a significantly larger decrease in fatigue compared to the waiting list [mean difference -8.1, 95% confidence interval (CI) -3.8 to -12.4, controlled effect size 0.70]. There was no significant difference in physical and social functioning. However, post-hoc analyses showed a significant decrease in fatigue and physical disabilities following the intervention in a subgroup of patients with physical disabilities at baseline (SF-36 physical functioning 70). CONCLUSIONS: Implementation of guided self-instruction in a community-based MHC was partially successful. The minimal intervention can be effectively implemented for CFS patients with physical impairments.