Background: Among 5 subfamilies of dopamine receptors (DAR), D3 and D5 DAR are expressed on peripheral blood mononuclear cells (PBMC). Recently, those DARs have been reported to change in Parkinson’s disease (PD). Methods: We measured the DAR mRNA expression in PBMC from 15 PD patients who had never taken antiparkinson medication, and 16 age-matched healthy people by reverse transcription and quantitative competitive polymerase chain reaction. The β-actin mRNA expression was also measured to evaluate the relative expression of DAR mRNA. Results: The D3 and D5 DAR mRNA expression was not different between patients and controls. In patients, no significant cor-relation was found between DAR mRNA expression in PBMC and clinical variables such as severity and duration of symptoms, and patients’ age. Conclusions: We confirmed the presence of D3 and D5 DAR in PBMC. However, their mRNA expressions were not influenced by the disease process of PD. J Kor Neurol Ass 17(3):359 ~ 364, 1999 Key Words : Parkinson’s disease, Peripheral blood mononuclear cell, Dopamine receptor, messenger RNA, PCR