Myalgic Encephalomyelitis/Chronic Fatigue Syndrome—commonly referred to as ME/CFS—is a legitimate, serious, and complex systemic disease that frequently and dramatically limits the activities of affected individuals, says a new report from the Institute of Medicine. The committee that wrote the report developed new diagnostic criteria for the disorder that includes five main symptoms. In addition, it recommended that the disorder be renamed "Systemic Exertion Intolerance Disease" and be assigned a new code in the International Classification of Diseases, Tenth Edition.