Thirty patients with restless legs syndrome, who initially had all responded well to treatment with levodopa and benserazide, were studied as to the long-term effect of the drugs (at least 2 years). During the 2-year period, two patients were switched from levodopa to bromocriptine. Two patients no longer needed levodopa; one of them had developed paraplegia and in the other the symptoms of restless legs syndrome had disappeared completely. The remaining 26 patients continued to use levodopa. Eight patients maintained the original dose, nine had to use an increased dose, and nine found a decreased dose to be sufficient. The only side effect was transient nausea reported by two of the 30 patients. The study showed that the relief of symptoms of restless legs syndrome by dopaminergic drugs does not wear off with the passage of time, that side effects are minimal even with long-term use, and that the dose needed to obtain relief may increase as well as decrease.