A levodopa/carbidopa/entacapone combination product (Stalevo) was recently approved to treat patients with idiopathic Parkinson's disease (PD) who experience end-of-dose "wearing-off." Stalevo is available in dose combinations of levodopa/carbidopa/entacapone 50/12.5/200 mg (Stalevo 50), 100/25/200 mg (Stalevo 100), and 150/37.5/200 mg (Stalevo 150). A series of pharmacokinetic studies demonstrated bioequivalence between Stalevo and corresponding dosages of levodopa/carbidopa plus entacapone. A clinical advantage of Stalevo is that patients can take one pill rather than two (or more) separate tablets. In addition, Stalevo 50 and 100 tablets are smaller than entacapone tablets. These advantages may be particularly beneficial for patients taking many pills, those who have difficulty following complex medication regimens, and those with swallowing difficulty. Most PD patients taking levodopa/carbidopa immediate-release (IR) plus entacapone can be directly switched to the corresponding dose Stalevo product. For fluctuating PD patients taking levodopa/carbidopa IR without entacapone, switching to the corresponding Stalevo tablet is analogous to adding entacapone. In switching patients who are receiving levodopa/carbidopa controlled-release (CR), it should be noted that the bioavailability of levodopa from levodopa/carbidopa CR is approximately 70-75% that of levodopa/carbidopa IR products, including Stalevo.