Chronic fatigue syndrome (CHS) [sic] is a long-term, often misunderstood disorder that affects multiple body systems. It’s also referred to as myalgic encephalomyelitis or myalgic encephalomyelitis/ chronic fatigue syndrome (ME/ CFS), chronic fatigue immunity deficiency syndrome, systemic exertion intolerance disease, and postviral fatigue syndrome.1-4 CFS affects more women than men and is more likely to occur in middle age, although it can happen at any age, including childhood.1-4 According to the CDC, an estimated 836,000 to 2.5 million Americans experience CFS, but most haven’t been diagnosed.3 This article describes the pathophysiology, signs and symptoms, diagnostic criteria, and nursing considerations for adult patients with CFS.