Functionally disabling chronic fatigue is a familiar complaint in adult primary care settings, infrequent among adolescents, and very rare in children. For more than a century, a syndrome of chronic fatigue associated with various physical and cognitive symptoms has been described with terms including neurasthenia, Akureyri disease, Royal Free disease, myalgic encephalomyelitis, postviral syndrome, and chronic fatigue syndrome (CFS). Scant data estimate that pediatric CFS has a prevalence ranging from 23 to 116 of 100 000 children and adolescents with an approximate 2.5:1 female to male ratio.1 Various diagnostic criteria have been proposed, but most researchers today use the 1994 Centers for Disease Control and Prevention (Atlanta, Ga) revised CFS criteria2 that require the presence of medically unexplained, profound, persistent or intermittent fatigue associated with significant functional disability for greater than 6 months and the presence of 4 additional symptoms (eg, headache, polyarthralgia, tender adenopathy, impaired memory). Those with at least 6 months of disabling fatigue but an insufficient number of symptoms to meet the Centers for Disease Control and Prevention CFS criteria have been labeled as having idiopathic chronic fatigue. While excluding most major psychiatric disorders, the Centers for Disease Control and Prevention criteria do allow some comorbid psychiatric symptoms, including anxiety and nonmelancholic depression, which may be problematic since both anxiety and depression have a well-established, independent relationship with fatigue.3