Recent studies suggest that Parkinson's disease (PD) is associated with particular personality traits. Using Cloningers's Tridimensional Personality Questionnaire (TPQ), Menza and colleagues [1993: Neurology 43: 505-508] reported a possible association between PD and a reduced score in the novelty seeking (NS) dimension of the TPQ. We sought to determine whether this association, which was found in a study conducted in the United States, could also be found among Japanese PD patients. We performed personality assessments of 67 Japanese PD patients, using the TPQ test. The results suggest that Japanese PD patients have significantly lower scores in the NS dimension of the TPQ, as well as significantly higher harm avoidance (HA) scores, compared with matched control subjects. Furthermore, the PD patients undergoing treatment for depression using antidepressant drugs scored significantly higher in the HA dimension than PD patients who did not receive antidepressant drug treatment. Our results suggest that the high HA score, and the low NS score in the TPQ test observed in patients with PD, is a cross-cultural phenomenon, although the influence of depression, longterm treatment, and premorbid gene/environmental interactions may also affect these personality traits.