Objective: Research of psychiatric disorders in Parkinson's disease (PD) patients. Method: Enrolled patients are evaluated by two psychiatrists via semi-structured interview. Hamilton Depresion Rating Scale (HDRS), Hamilton Anxiety Rating Scale (HARS), Geriatric Depression Scale (GDS), BEHAVE-AD-FW, Mini Mental Status Examination (MMSE), Unified Parkinson's Disease Rating Scale (UPDRS) and Shwab England ADL scales were applied to all patients. Findings: We diagnosed 22 patients (38.6%) as major depressive disorder, 1 patient (1.8%) as Obsesive Compulsive Disorder and 8 patients (14%) as Dementia. Scores of HDRS, HARS, GDS and UPDRS-section 1 were found higher in depressed patients compared to non-depressed patients. Also in depressed group the onset of PD was earlier compared to non-depressed patients (p<0,001 for scales, p<0.05 for age). A positive correlation was found between duration of PD and HARS (p<0,001, r:0.271) and BEHAVE-AD-FW (p<0,05, r:0,298). Discussion: We found that major depressive disorder is the most common psychiatric disorder in PD; however, we found no relationship between depression and the motor signs of PD. The number of detected depressive patients by the cut off point of GDS and the number of depressive patients detected by psychiatric interview did not differ. We assume that depression was accompanied by anxiety and cognitive impairments. Conclusion: More progressive studies with larger samples are needed to evaluate psychiatric disorders and their treatment which may contribute the progress of the disorder.