Background: The preferred surgical target for the treatment of Parkinson disease (PD) is either the internal globus pallidus or the subthalamic nucleus (STN); the target for treatment of essential tremor (ET) is the thalamic subnucleus ventralis intermedius (Vim). Some patients with PD have coexistent ET, and the identification of a single surgical target to treat both parkinsonian motor symptoms and ET would be of practical importance. Objective: To describe the use of the STN target in deep brain stimulator (DBS) surgery to treat PD motor symptoms and the action-postural tremor of ET. Design: Case report. Patient: A 62-year-old man had a greater than 30-year history of action-postural tremor in both hands, well controlled with β-blockers for more than 20 years. He developed resting tremor, bradykinesia, and rigidity on his right side that progressed to his left side during the past 10 years. Dopaminergic medication improved his rigidity and bradykinesia, with only mild improvement of his resting tremor and no effect on his action-postural tremor. Interventions: Left pallidotomy followed by placement of a left DBS in the Vim and subsequent placement of a right STN DBS. Main Outcome Measures: Control of symptoms of PD and ET. Results: The left pallidotomy controlled the patient's parkinsonian motor symptoms on the right side of his body, but did not affect the action-postural component of his tremor. The symptoms on the left side of the body, including both an action-postural and a resting tremor (as well as the rigidity and bradykinesia), improved after placement of a single right STN DBS. Conclusion: Placement of an STN DBS should be considered as the procedure of choice for surgical treatment of patients with a combination of PD and ET.