This study was designed to investigate the influence of white matter hyperintensities (WMH) on clinical features of Parkinson's disease (PD) patients. The study subjects were 44 patients with PD who took a brain MRI. The severity of Parkinsonian symptoms was assessed in both 'on' and 'off' states, using the UPDRS-motor score. Thirteen patients (30%) showed WMH. The patients with WMH were significantly older than those without WMH (67 ± 5.7 vs 60 ± 6.4 years). In both 'off' and 'on' states, the gait scores were significantly higher in patients with WMH than in those without WMH (1.6 ± 0.18 vs 1.1 ± 0.12, P < 0.05), but other motor symptom (tremor, bradykinesia, rigidity) scores between the two patient groups were not statistically different. After taking a single dose of oral levodopa/benserazide (200mg/50mg), the patients with WMH showed significantly less improvement in bradykinesia score than those without WMH (25 ± 4.1% vs 40 ± 4.0%, P < 0.05), but the improvements in other symptoms were comparable between the two groups. These results suggest that WMH on MRI may influence Parkinsonian motor symptoms, particularly gait symptom and levodopa-responsiveness to bradykinesia symptom.