Background: Restless legs syndrome (RLS) is characterized for an uncomfortable sensation in legs and an irresistible desire to move them. This disorder has been more recently recognized in patients with myasthenia gravis (MG) and can interfere with the quality of life (QOL). Objectives: The aims of this study are to describe the prevalence of RLS and its severity and influence on the QOL in patients with MG. Method: This was a cross-sectional study conducted from May to June 2016 in Recife, Brazil. A sample of 42 patients was interviewed using a sociodemographic questionnaire, MG QOL questionnaire-15 and The RLS Rating Scale. Results: RLS was present in 47.6% of patients and of these 40.5% met moderate to severe RLS criteria. Patients were 45 years on average (SD ± 14.4) and women represented 57.1% of the study population. Among patients with RSL, the quality-of-life scores were worse (p = 0.010) on average. There was no association of RLS with the duration of MG, use of immunosuppressant or clinical conditions that could mimic the occurrence of RLS. Conclusion: RLS is a prevalent condition in patients with MG, and may be severe enough to negatively impact QOL.