Restless legs syndrome (RLS) is a common condition characterized by uncomfortable sensations deep in the legs, developing at rest, that compel the person to move. Symptoms are worst at night and sleep disturbance is common. RLS occurs in 7–11% of the population in western countries, and is increasingly common in older people. Primary RLS is familial in up to two-thirds of patients. RLS may also be secondary to a number of conditions, including iron deficiency, pregnancy and end-stage renal failure and, perhaps, to neuropathy. Secondary RLS is most common in those presenting for the first time in later life. The pathogenesis of RLS probably involves the interplay between systemic or brain iron deficiency and impaired dopaminergic neurotransmission in the subcortex of the brain. Dopamine agonists are the first-line treatment for those requiring pharmacotherapy; however, correction of underlying problems, in particular iron deficiency, is also important.