This study reviews empirical evidence on the association between personality traits and Parkinson's disease (PD), with a twofold aim. First, to better identify non-motor symptoms, such as affective symptoms and personality changes, that could help to define the pre-motor phase of PD; second, to better understand the neurobiological bases of personality traits, a goal that is not fully accomplished by a purely anatomical approach. A literature review was performed on studies of personality traits in PD patients, in electronic databases ISI Web of Knowledge, Medline and PsychInfo, conducted in July 2011. We found evidence that the existence of a characteristic premorbid personality profile of PD patients is not actually sustained by robust empirical evidence, mainly due to the methodological bias of the retrospective assessment of personality; PD patients present a personality profile of low novelty seeking and high harm avoidance. We concluded that the definition of a pre-motor phase of PD, based on non-motor symptoms, should search for the presence of concomitant affective disorders and for a positive psychiatric history for affective disorders rather than for a typical personality profile or personality changes. The low novelty seeking profile is probably related to the dopaminergic deficit, while the high harm avoidance profile is probably associated with the presence of affective disorders. Clinical implications of these findings, in regard to personality assessment and pharmacological treatments in PD, are also discussed.