Background: Restless leg syndrome (RLS) has negative effects on the quality of life of the patients. Epidemiological studies on RLS are limited. Aim: To determine the prevalence of RLS among people aged 40 years and above in Orhangazi district of Bursa, Turkey. Materials and Methods: The study was carried out between 2004 and 2005. This population-based study was conducted in two phases. In the phase 1, residents conducted door-to-door interviews using a short questionnaire to determine the possible cases of RLS. In the phase 2, physicians ascertained the suspected cases of RLS. Diagnosis of RLS was made using the criteria proposed by the International Restless Legs Syndrome Study Group (IRLSSG) and also the rating scale for RLS. Results: Out of 1, 256 subjects screened in phase 1, 1,124 (89.6%) were included in the study. Also, 161 cases with suspected symptoms of RLS were detected in phase 1, 49 of the suspected cases could not be evaluated in phase 2. A diagnosis of RLS was also made in 60 cases during phase 2. Conclusions: We defined the prevalence of RLS as 9.71% among 40 years of age and older population. The prevalence of RLS did not differ by age and was 2.6 times more in women. None of the patients were diagnosed as RLS sought medical care for the symptoms, possibly due to lack of knowledge of patients and physicians about RLS. Prevalence studies help to provide knowledge on morbidity, which is essential for diagnosis and early treatment.