OBJECTIVES: This study was carried out to determine the responsiveness, test-retest reliability and the minimally important difference (MID) of the 8-item Parkinson’s disease Questionnaire (PDQ-8) in Asians with Parkinson’s disease (PD) in Singapore. METHODS: A convenience sample of PD patients attending a tertiary neuroscience clinic in Singapore completed the English or Chinese version of PDQ-8 twice during two different clinic visits. On the second visit, patients also rated changes in their health in general, their PD severity, and the overall impact of PD on their life using a 5-point response scale (i.e., a lot better, a little bit better, about the same, a little bit worse, and a lot worse). RESULTS: A total of 96 patients participated in the study. For patients who reported better conditions in the second visit, Cohen’s effect size, standardized response mean and responsiveness statistic ranged from -0.58 to -0.21; for patients who experienced worse conditions, the responsiveness index values ranged from 0.24 to 0.68. The intra-class correlation coefficient calculated using stable patients ranged from 0.64 to 0.76. MID values estimated using the anchor-based method ranged from 5.8 to 7.4. CONCLUSIONS:The PDQ-8 instrument is longitudinally valid in Singaporean patients with PD. The MIDs estimated in the study can be used for sample size calculation and interpretation of treatment benefits in clinical trials where the PDQ-8 summary index is used as the primary outcome measure.