Background: Restless legs syndrome (RLS) is a disorder characterized by disagreeable sensations in the legs that occur at rest and are relieved by movement. These symptoms, which are worse at night, may result in sleep onset or sleep maintenance insomnia. Most patients are found on polysomnography (PSG) to have periodic limb movements in sleep (PLMS). The disorder, idiopathic in most cases, may be sometimes associated with specific disorders.Methods: Using the Province of Manitoba Health database, we compared the diagnoses made in the 5 years prior to sleep laboratory evaluation of 218 patients (103 men and 115 women) with RLS and 872 matched control subjects from the general population.Results: We found that 43.7% of male RLS patients vs. 10.4% of male controls and 46.1% of female RLS patients vs. 22.8% of female controls had been diagnosed as having psychological/psychiatric (most often depression) disorders (P<0.05). Extrapyramidal disease or movement disorders were previously diagnosed in 17.5% of male RLS patients vs. 0.2% of male controls and in 23.5% of female patients vs. 0.2% of female controls (P<0.05). Many patients had been previously diagnosed with disorders of the musculoskeletal system: 35.9% of male patients vs. 22.8% of male controls and 49.6% of female RLS patients vs. 23.3% of female controls had been diagnosed as having diseases of joints (male; P=ns, female; P<0.05). Disorders of the back were also more frequently diagnosed in RLS patients: 21.4% of male patients vs. 13.1% of male controls and 38.3% of female patients vs. 15.0% of female controls (male; P=ns, female; P<0.05).Conclusions: We conclude that RLS patients are much more likely to have previously been diagnosed with extrapyramidal disorders, musculoskeletal disorders, depression, and painful conditions such as joint and back disorders.