Nelonicline (0.03 mg/kg) treatment, has no significant effect on LIDs. The effect of Nelonicline (1.0 mg/kg) is also tested for its ability to reduce LIDs at a higher dose of L-dopa (15 mg/kg)/carbidopa (3.75 mg/kg). The higher dose of L-dopa leads to greater LID scores in vehicle-treated monkeys. Nelonicline treatment reduces LIDs by 70%, after the morning dose of L-dopa and 60% after the afternoon dose. The effect of Nelonicline is most pronounced during the latter weeks, possibly because of a greater decline with continued drug treatment. Nelonicline (0.10 mg/kg)treatment, decreases LIDs by ~40%, while the 0.30 and 1.0 mg/kg Nelonicline doses decrease LIDs up to ~60%. These data indicate that Nelonicline would be useful as an antidyskinetic drug in Parkinson's disease.