OBJECTIVE: Pallidotomy is known to improve the symptoms of idiopathic Parkinson, s disease (PD), motor fluctuations and dyskinesia related to levodopa therapy. Previous studies reported significantly higher complication rates associated with bilateral pallidotomy than unilateral pallidotomy. The authors assess the safety and clinical outcomes of bilateral pallidotomy for advanced PD. METHODS: Simultaneous bilateral pallidotomy was performed in eight patients with advanced PD between January 1, 2001 and December 31, 2001. All patients underwent lesion making in posteroventral site of internal globus pallidus. The target was localized using macroelectrode stimulation and MRI guided stereotactic technique. The lesions were made by radiofrequency currents. RESULTS: Among eight cases, seven had severe disabling dyskinesias. Compared with baseline scores, the values of dyskinesia after surgery was significantly decreased (P<0.05) for up to 1 year. The mean score changed from 4.4+/-2.1 to 0.3+/-0.5. According to Unified Parkinson's Disease Rating Scale (UPDRS), the mean motor score in off period, which was 38.3+/-13.8 was significantly decreased for 6 months (P<0.05). The ADL (on/off) scores and motor "on" scores of UPDRS were unchanged or deteriorated to 12 months after surgery. There was no apparent adverse effect after surgery in all patients. Only transient mild dysphagia happened in one patient. CONCLUSION: Simultaneous bilateral pallidotomy in advanced PD appears to be effective and safe, particularly in reducing the dyskinesia; in our experience, the side effects are not as high as reported by other groups.