Perhaps one of the most exciting developments in brain research of the past decade is the advent of genetic intervention in human neurologic disease. Although there are a variety of gene transfer approaches, none of which has been perfected, gene therapy is now science fact and no longer science fiction. As technology progresses, some vectors will prove more effective for certain disease categories than others; it is too early to predict definitively which vector would be most effective for therapy in Parkinson's disease and other movement disorders. Nonetheless, it is likely that within the next year or two a gene therapy trial will be instituted in human patients with Parkinson's disease. The potential for an impact on the symptoms and progression of this disease is significant. Clinicians may be on the threshold of a new era of intervention for Parkinson's disease and other neurologic diseases, based on bypassing traditional but less selective drug-extracellular receptor interactions and instead focusing on genetic modulation of specific intracellular processes. The continuing development of small incremental changes of new dopamine agonists and pharmacologic agents will likely pale in comparison to the specificity of intracellular genetic manipulation.