Objectives: The aim of this study was to investigate 1) the prevalence of depressive symptoms, 2) the severity of depressive symptoms, 3) the correlation of depressive symptoms with clinical variables, and 4) factors that contribute to depressive symptoms in patients with Parkinson's disease. Methods: One hundred eighteen patients with Parkinson's disease referred from the Parkinson's Disease Clinic of Dong-A University Hospital, Busan, Korea, completed a self-administered questionnaire package, which included basic demographic data, the Beck Depression Inventory, the Parkinson's disease quality of life questionnaire, the Symptom Checklist-90-Revision(SCL-90-R), and the Spielberger's State-Trait Anxiety Inventory. In addition, a structured interview and a complete neurological examination, including the Hoehn and Yahr stage, the motor part of the Unified Parkinson's Disease Rating Scale(some selected scales of UPDRS part III), the Schwab and England Activities of Daily Living scale(ADL), and the Korean version of Mini-Mental State Examination were performed. Results: 1) Based on BDI score, subjects were divided into four groups:severely(40.7%), moderately(13.6%) and mildly(12.7%) depressive and non-depressive(33.1%). 2) The severity of depressive symptom in Parkinson's disease was positively correlated with Hoehn and Yahr(H & Y) stage(r=0.34, p<0.0001), the severity of motor symptom(r=0.35, p<0.0001), and trait anxiety inventory(r=0.33, p<0.001). On the other hand, the severity of depressive symptom was negatively correlated with educational level(r=-0.34, p<0.001), ADL(r=-0.37, p<0.0001) and Parkinson's disease quality of life (PDQL)(r=-0.69, p<0.0001). Among several clinical variables, the PDQL was the most influential factor predicting whether the depressive symptom was present or not. Conclusion: This study suggests that depressive symptom is very prevalent among patients with Parkinson's disease. Data from this study indicate that medical staffs who take care of patients with Parkinson's disease should pay attention to finding and treating depressive symptom among their patients. With appropriate psychiatric intervention, patient's depressive symptom can be minimized or alleviated and thus, the quality of life in these patients is likely enhanced.