Synchronization of neuronal activity within and across distributed brain regions is a fundamental property of cortical and subcortical networks and serves a variety of functions including motor and cognitive processes. Data will be reviewed here from cross-sectional EEG and MEG studies to suggest that Parkinson's disease is characterized by changing patterns of disturbed neural synchrony that appear to be dependent on the stage of disease. Some of these alterations in neural synchrony may directly account for a number of disease-related impairments in motor and cognitive functions. Future longitudinal studies are required to fully understand the disturbances of functional brain networks in Parkinson's disease and how they evolve throughout the course of the disease.