Sixteen patients with symptoms of restless legs syndrome and resulting insomnia are included in this study. They were nine women and seven men with a mean age of 50.8 years and with a mean duration of symptoms of 6.3 years. The purpose of the study is to determine the drugs that are useful for the treatment of restless legs syndrome. In 13 patients L-Dopa plus benserazide, in two patients bromocriptine, and in the remaining one patient piribedil were used orally at night approximately 1 h before bedtime. Compared with placebo these dopaminergic drugs decreased the times of waking up and staying awake periods at a statistically significant level (p changed between 0.025 and 0.01, t test). In this susceptibility of CNS there is dysfunction of the dopamine system triggered by sleep, and resting and dopaminergic potentiation by drugs affect the symptoms.