The study was aimed to examine the prevalence of depression in patients with Parkinson's disease (PD) and identify its features. A total of 131 out-patients, diagnosed as having idiopathic PD in accordance with the United Kingdom Parkinson's Disease Society Brain Bank criteria, were interviewed with questionnaire and evaluated by Mini-Mental State Examination (MMSE), Unified Parkinson's Disease Rating Scale (UPDRS), Hohen &Yahr staging (H&Y staging) and Hamilton Rating Scale for Depression (HRSD). Patients were divided into three groups in terms of HRSD score: depression group, sub-threshold depression group and non-depression group. The clinical variables and symptom profiles were obtained and compared among the three groups. The results showed that 27 patients (20.6%) fell into the depression group, 71 (54.2%) into the sub-threshold depression group, and 33 (25.2%) into the non-depression group. There were no differences in age, gender or tremor score among the groups (P>0.05). Significant differences were found in duration of PD, UPDRS score, rigidity score and H&Y stage between the sub-threshold depression group (or the depression group) and the non-depression group (P<0.05). Moreover, the clinical variables in the subthreshold depression group had the trend of increasing with the severity of PD and their values were similar to those in the depression group. Anhedonia, feeling of incapability, sleep disturbance, gastrointestinal symptoms and depressive moods were most common in the depression group. And these symptoms also were more common in the other two groups. It is concluded that depression and sub-threshold depression are common in PD and share similar clinical features. Furthermore, subthreshold depression might be the prodrome of depression and may develop into depression as the condition progresses.