The pathology of Parkinson's disease (PD) is not confined to the brainstem regions, but spreads to involve the neocortical areas. Using surface-based cortical thickness analysis, we studied the topographical distribution of cortical thinning in nondemented patients with mild PD. The high-resolution magnetic resonance imaging (MRI) studies were performed in 48 patients with PD without dementia and 56 age-matched healthy controls. Using the Freesurfer software, surface-based analysis was done to find changes in cerebral cortical thickness in patients with PD. Compared to the controls, patients with PD showed significant cortical thinning in the temporal, inferior parietal, rostral frontal, and orbitofrontal cortical areas. Thinning of the cerebral cortex occurs even in nondemented patients with mild PD, and its topographical distribution was similar to that of the neocortical Lewy bodies. Further studies are needed to find pathological and clinical correlates of thinned cerebral cortex found in nondemented patients with mild PD.