The psychometric properties of the Dutch version of the Parkinson's disease questionnaire 39 (PDQ39-DV) were tested in 177 patients with Parkinson's disease (PD). Internal consistency of 7 of the 8 scales was adequate (>or=0.70), but was insufficient for 'bodily discomfort' (0.59). Correlation between the PDQ39 and other instruments in this study, the SCOPA-psychosocial questionnaire, Euroqol-5D, hospital anxiety and depression scale, and a visual analogue scale for quality of life, were 0.82, 0.74, 0.63 and -0.54, respectively. The factor analysis yielded 8 factors, which accounted for 65% of the variance and revealed only small differences with the original UK version. We conclude that the PDQ39-DV displays satisfactory psychometric properties and is an appropriate instrument to assess quality of life in Dutch patients with PD.