<b><i>Background:</i></b> Restless legs syndrome (RLS) is a common sleep disorder, although it has a low prevalence in Asian populations. However, the reported RLS prevalence in ­Korean adults is mostly 4.5–12.1%, which is higher than that reported in other Asian populations. This study aimed to diagnose RLS and exclude mimicking conditions in 2 independent samples of Korean adults, and to compare its prevalence to that from previous studies performed in Asian countries. <b><i>Methods:</i></b> Study populations included a (1) nationwide stratified random sample (<i>n</i> = 2,824; age 19–79 years) and (2) community-based cohort (<i>n</i> = 2,685; age 47–79 years). We applied the Cambridge-Hopkins diagnostic questionnaire to diagnose RLS and differentiate it from RLS mimics. Sleep-related symptoms, mood, and medical conditions were compared between the RLS and non-RLS groups. Prior studies of the RLS prevalence in Asia were systematically reviewed and compared to our findings. <b><i>Results:</i></b> The adjusted RLS prevalence was 0.4 and 1.3% in populations 1 and 2, respectively. In both populations, subjects with RLS had more depression. The prevalence of RLS mimics was 5.1 and 2.6%, in populations 1 and 2, respectively. The RLS prevalence in Asia was higher when RLS was defined by the presence of essential clinical features and lower when a differential diagnosis was additionally implemented. <b><i>Conclusions:</i></b> The RLS prevalence in Korean adults considering RLS mimics is comparable to that in adults from other Asian countries (&#x3c; 2%). The reported RLS prevalence varies depending on the diagnostic method employed.