Restless leg syndrome (RLS) is characterized by intense restlessness and unpleasant creeping sensations deep inside the lower legs, occurring during periods of rest, evening and night. These symptoms can be improved by movement. There are two different phenotypes of RLS. One early-onset form starts before 36 years old. It has mostly a familial history, severe symptoms, and highly genetically determined. And it is a highly dependent to iron level of the brain. The other delayed-onset form starts after 36 years old, mostly secondary, without familial history, with a rapid evolution in two or three years. And it is associated with frequent low ferritin level of serum. Pathophysiology of RLS remains incompletely understood. However, advanced studies suggest that RLS may be generated by dopamine dysfunction locally within the central nervous system. Dopaminergic agonists are the treatment of choice, if the symptoms are severe. And iron therapy improves RLS symptoms in iron deprived patients. Early detection during pregnancy is needed because RLS gives an important impact on sleep efficiency and quality of life. Recently we have experienced a case of primary RLS patient diagnosed at 24+3 weeks, treated by dopaminergic agonist ropinirole and iron. We describe this case with a brief review of the literature.