Restless legs syndrome (RLS) is believed to be a condition primarily of middle to older age. However, it can have its onset in childhood. Five illustrative case histories with an autosomal dominant mode of inheritance are described. A mother and her 3 children (age: 6 1/2, 4 and 1 1/2 years) as well as a 16-year-old patient from a second family have typical RLS signs of leg discomfort (paresthesias) and motor restlessness prevalent at night and at rest, with temporary relief by activity. Polysomnography or videotaping revealed periodic limb movements in sleep (PLMS) and, in some cases, involuntary jerking of the legs was present during wakefulness as well. Clinicians should be aware that RLS can occur in childhood and adolescence and may be more common than heretofore recognized. "Growing pains" and attention deficit hyperactivity disorder (ADHD) are in the differential diagnosis of RLS in childhood.