RLS is common and may be under-diagnosed. In the US, up to 8% of the population may have RLS. Recent evidence suggests that at least 5.8% of men in Sweden have RLS. Similar data is not yet available for the UK. Available evidence suggests that at least in European and US populations of European extraction, RLS may be the most common of the movement disorders (even more common than benign essential tremor). There is little data about the prevalence of RLS in non-white ethnic groups. Pilot studies from Singapore and India suggest that prevalence of RLS may be low in Singapore Chinese and Indian origin patients but these observations need to be confirmed in larger studies. There is no data related to prevalence of RLS in African-Caribbean or African origin subjects.

Many patients may have a mild form of RLS but in approximately 20% symptoms may be severe and disabling and may merit specific and specialist treatment.