Recent interest in cognitive behavioural therapy techniques for treatment of Chronic Fatigue Syndrome (CFS) has highlighted the contribution of psychological approaches to alleviating the debilitating symptoms of this illness. In previous research sufferers from CFS have been compared with depressed patients and patients with neuromuscular disease, as they share similar symptoms, but not diagnosis. This study attempts to compare four groups including a normal working group. A new measures was developed and piloted, designed to measure interpretations of symptoms in CFS. In addition standard instruments were used to focus on the measurement of high personal standards, perfectionism, emotional control and conscientiousness and levels of autonomy. Results showed the CFS group were similar to the normal working group on all standard scales and scored low on autonomous personality traits. Reasons for this result, and the clinical implications for treating such a heterogeneous patient group are discussed. Measures on the symptom interpretation scale show CFS patients are less likely to give an emotional explanation for their symptoms than the other participant groups. This has implications for communication between physician and patient, and the treatment of CFS with a psychological model.