Objective: To examine the relationship between a history of childhood maltreatment and the treatment response to cognitive behavior therapy for chronic fatigue syndrome (CFS). Methods: A cohort study in a tertiary care clinic with a referred sample of 216 adult patients meeting the Centers for Disease Control and Prevention criteria for CFS, and starting cognitive behavior therapy. Main outcome measures changes between pre- and post therapy in fatigue (Checklist Individual Strength fatigue subscale), disabilities (Sickness Impact Profile total score), physical functioning (short form 36 health survey subscale) and psychological distress (Symptom checklist 90 total score). Results: At baseline, patients with a history of childhood maltreatment had significantly more limitations and a higher level of psychological distress, but were not more severely fatigued. Change scores on the outcome measures after cognitive behavior therapy did not differ significantly between patients with or without a history of childhood maltreatment, or between the different types of childhood maltreatment. However, patients with a history of childhood maltreatment still experienced more limitations and a higher level of psychological distress after CBT. Conclusions: A history of childhood maltreatment was not related to the treatment response of cognitive behavior therapy for CFS. In patients with a history of childhood maltreatment CFS symptoms can be treated with CBT just as well as those without. (C) 2011 Elsevier Inc. All rights reserved.