Randomised, double-blind, double dummy, parallel group design. Following the screening period patients will be randomised at the baseline visit, in a 1:1:1 manner, to one of three treatment arms; 4 mg E2007, 200 mg entacapone (with each dose of levodopa) or placebo. The first 4 weeks of the double blind phase will be used to titrate patients on the E2007 arm from 2 mg up to the maintenance dose of 4 mg. Patients randomised to entacapone or placebo will have dummy up titrations to maintain the blind. Following this titration phase, patients will remain on the maintenance dose for a further 14 weeks.