Driving in Parkinson's disease. Altered motor or mental skills in Parkinson's disease (PD) could adversely affect driving ability. We interviewed 150 patients regarding their driving habits and compared them with 100 controls. Thirty patients had stopped driving because of PD. PD patients had no more lifetime accidents than controls. With increased disability, however, there was a smaller percentage of patients still driving with fewer miles traveled and with proportionately more accidents occurring. Though disability scores did not correlate well with driving ability, there were significantly more accidents in subjects with more severe PD. The presence of cognitive impairment was associated with an increased accident rate. We conclude that driving in PD may be a public health problem and that some PD patients should not drive. 