This study seeks to get around that problem using a controlled clinical trial that compares the embryonic dopamine cell implant surgery with a placebo treatment. A total of 40 patients were recruited--half received the cell implant surgery, while the other half received the placebo. After the double-blind phase of the study, patients in the placebo group had the option of receiving tissue implants. Fourteen of these patients eventually had transplants. At present, this study is providing long-term follow-up evaluation and treatment for the subjects.