Depression and antidepressant use are common in Parkinson's disease, but the benefit of selective serotonin reuptake inhibitor (SSRI) treatment in this population has not been established. The authors treated 14 Parkinson's disease patients with major depression with escitalopram in an open-label study. Although treatment was well tolerated and correlated with a significant decrease in Inventory of Depressive Symptomatology score, response and remission rates were only 21% and 14%, respectively. However, half of the subjects met Clinical Global Impression-Improvement criteria for response. In Parkinson's disease, either SSRIs may have limited antidepressant effects, or the use of existing depression diagnostic and rating instruments may be problematic.