The purpose of this study was to investigate the frequency of depression and the relationships between various clinical features and depression in the patients with idiopathic parkinsonism. We included 113 patients of idiopathic parkinsonism who had any three of resting tremor, rigidity, bradykinesia, impaired postural reflexes or any one of the first three displaying asymmetry without definite brain lesion on brain imaging studies or metabolic derangement. We used Beck depression inventory, and the results were compared with those of 70 normal controls. The following results were obtained: 1.The patients with idiopathic parkinsonism had more severe depression than normal controls. If we@ consider the cut-point scores for depression as more than 21points of Beck depression inventory scores, the frequency of depression in idiopathic parkinsonism was 44. 1%. 2.The scores of the BDI questionare representing somatic symptoms were increased in the patient group, whether they had mild or severe parkinsonian deficits. The patients who had more severe parkinsonian deficits had higher scores. However, those representing mood and self-reproach symptoms were increased only in the late stage of idiopathic parkinsonism. 3.The severe motor symptoms, particularly bradykinesia and rigidity, poor responsiveness to L-dopa treatment, longer the duration of disease, were the factors correlated with severe depression. However the current age, age of onset, whether treated or untreated, and whether sy7rnptonis affected predominantly right or left side of the body, were not correlated with the severity of depression. On the basis of the results, when we regard no tremorous symption and the poor responsiveness to L-dopa treatment as the clinical features of idiopahtic parkinsonism, we suspect the tendency that the patients with idiopathic parkinsonism may have more severe depression than those with idiopathic P-qrkinson's disease.