OBJECTIVE: To describe the long-term outcome in 50 consecutive advanced Parkinson's disease (PD) patients treated with subthalamic nucleus deep brain stimulation (STN-DBS). METHOD: Assessments were carried out at baseline, 6 months, 2 years, and 5 years postoperatively. RESULTS: Compared to baseline scores without medication, we found a highly significant improvement of UPDRS III with stimulation, maintained at 5 years (p<0.001). This improvement, however, tended to diminish over time. Dyskinesia and off periods were also improved (p<0.0001 for both). Seventeen patients died during follow-up, who tended to be older at surgery (p<0.01). CONCLUSIONS: STN-DBS is an effective treatment for advanced PD patients, and the beneficial effect is maintained at 5 years. However, worsening occurs over time due to disease progression.