Twenty-seven patients with idiopathic Parkinson's disease completed a double-blind crossover trial which compared enteric-coated levodopa (Prodopa) with levodopa–carbidopa combination (Sinemet). It was easy to stabilize the patients’ condition with either drug, and the dose-sparing effect both of the enteric-coated preparation, and of the levodopa–carbidopa combination was again noted. At the dosages used, the levodopa–carbidopa combination was objectively shown to be more effective in 71% of the patients investigated, although there was no clear personal preference for either preparation when patients compared the two parts of the trial. Both drugs play a valuable role in the treatment of Parkinson's disease.