Musculoskeletal pain is one of the most common pains of adolescence, along with headache and abdominal pain, and arthralgia is the single most common reason for referral to the pediatric rheumatologist. Not surprisingly, the pediatric rheumatologist is frequently called to distinguish organic from functional symptoms. During the past decade, the pediatric rheumatology community has been evaluating increasing numbers of adolescents and preadolescents who experience musculoskeletal symptoms presumably as a defense against emotional stress from achievement either in academic work or in sports. To complicate the challenge further, coexistent organic and psychologic disturbance is not rare. Clearly, organic illness does not protect a patient from emotional plan, and it may be most difficult to differentiate nonorganic pain in a patient with a known organic illness. Conversely, adolescents with organic illness may use their disease for secondary gain. Fear of misdiagnosis of physical illness as psychiatric and the notion that all of the patient's complaints should be explained by a unifying diagnosis cause diagnostic error in both psychogenic illness with physical manifestations and physical illness with psychogenic symptoms.