Objective: This study aimed to compare the half-effective concentration (EC50) of propofol required for the bispectral index (BIS) 50 in patients with Parkinson's disease (PD) and non-PD (NPD) during induction by the Dixon's improved sequential method. Methods: This prospective study recruited 20 patients with PD undergoing deep brain stimulation and 20 patients with NPD accompanied by meningioma or glioma undergoing intracranial surgery from March 2018 to March 2019. The patients were induced by propofol via target-controlled infusion. The target effect-site concentration of propofol was determined by the Dixon's improved sequential method. The results of the pilot experiment showed that the target effect-site concentration for the first patient with PD and NPD was 3.5 mu g/mL and 2.8 mu g/mL, respectively. BIS values were recorded after achieving a constant effect-site concentration of propofol. The increment or decrement of the target effect-site concentration of the next patient was 0.1 mu g/mL.Results: Demographic data, general physical condition, and hemodynamic values were similar between the PD and the NPD groups. The target effect-site concentration of propofol induction doses was significantly higher in the PD group than in the NPD group. The EC50 of propofol required for BIS 50 was 3.213 mu g/mL [95% confidence interval (CI), 3.085-3.287 mu g/mL] in the PD group and 2.77 mu g/mL (95% CI, 2.568-2.977 mu g/mL) in the NPD group. Conclusion: The EC50 of propofol required for BIS 50 was higher in patients with PD than in patients with NPD.