For many patients with Parkinson's disease and levodopa-related motor fluctuations, the latency to onset of action of a single dose of a standard levodopa preparation may be both long and variable. The long-acting levodopa preparations now available have a very long latency to turn “on” patients because of their pharmacokinetic characteristics. This article reports the results of a previous study on the clinical efficacy of a single morning dose of levodopa methylester (250/50), Madopar Dispersible (2 × 100/25), and Sinemet Plus (2 × 100/25). We also report the preliminary results of a clinical and pharmacokinetic study comparing the single administration of Madopar HBS (HBS) and the combination of HBS with either Madopar Dispersible or Madopar 125 mg. The results of the first study show that the liquid forms of levodopa are quicker to produce the clinical response than the solid forms. The preliminary results of the second study show that the combination of Madopar Dispersible and HBS may provide clinical advantage in fluctuating parkinsonian patients, ensuring a short latency to “on” and a prolonged clinical effect.