BACKGROUND: The goal of therapeutic interventions for Parkinson's Disease (PD) is to improve the symptoms and mitigate the effect on the Quality of Life (QOL) in the individual patient. The purpose of this study was to investigate QOL and related factors in PD patients in Korea. METHODS: Between January 1, 2004 and July 15, 2004, eighty-one PD patients were included. The patients were assessed using Parkinson's Disease Quality of Life (PDQL), Modified Beck Depression Inventory (BDI), and K-MMSE. RESULTS: Twenty-five male and 56 female patients were included in the study. The mean age was 60.7 years and the mean disease duration was 7 years. The male patients (p=0.07) and young age at onset (p=0.07) showed borderline correlation with PDQL score. Medical cost for PD showed significant correlation with PDQL score (p<0.001). The patients working in the daytime or spending the daytime with their spouse showed significantly higher PDQL score than those who did not (p=0.01). Among the disease characteristics, the disease duration, levodopa dosage, UPDRS score, ADL, Hoehn and Yahr stage, the presence of motor fluctuation and dyskinesia, showed that depression had a strong correlation with the PDQL score (p<0.001). On the stepwise regression analysis, the most important factor was presence of depression, disease duration and the UPDRS total score in order of strength. CONCLUSIONS: The QOL in PD patients was strongly associated with depression, disease duration, and the severity of PD. We suggest that the assessment and proper management of depression as well as other PD symptoms is necessary to improve QOL of the PD patients.