Patients with restless legs syndrome (RLS) suffer from sensory and motor symptoms evoked in the limbs at rest. Symptoms increase in the evening and during the night. The circadian rhythm and the presence of involuntary periodic limb movement in sleep (PLMS) which are frequently associated with arousals probably cause the leading symptom of sleep disturbances in RLS. Patients who do not have typical RLS symptoms but whose polysomnography shows PLMS that either impact on sleep continuity or daytime functioning are diagnosed as having the periodic limb movement disorder (PLMD). Dopaminergic agents such as levodopa/dopa decarboxylase inhibitor (DDI) and dopamine agonists are considered the treatment of choice for RLS and PLMS. This article gives an overview of the epidemiology, pathophysiology, clinical symptomatology and diagnosis of RLS and PLMD and focuses on treatment strategies in both disorders.