ABSTRACT
The purpose of this study was to examine if type of Chronic Fatigue Syndrome (CFS) onset suggested two distinct illness patterns within CFS. One hundred and seventeen patients diagnosed with CFS by a multidisciplinary team were divided into two groups: sudden versus gradual onset of symptoms. These two subgroups were compared on the presence of lifetime comorbid Axis I diagnoses, the pattern of medically unexplained symptoms, and the number of patients who met criteria for Somatization Disorder (SD). The two subgroups did not differ in any of the experimental variables indicating that onset type is not distinguished by either comorbid psychopathology or medically unexplained symptoms. Implications of these findings are discussed.