Background: Oxidative stress is implicated as a major factor for nigral neuronal cell death. It has been suggested that nitric oxide (NO) might be responsible in the neuronal degeneration of substantia nigra compacta in patients with Parkinson’s disease (PD). Methods: To elucidate the possible role of NO as a risk factor for PD, we determined the plasma levels of nitrate in 80 PD patients and 80 age and sex-matched controls. Results: There was a signifi cant difference between the mean plasma nitrate level of PD patients (34.5 ± 4.2 μmol/l) vs. controls (31.8 ± 3.15 μmol/l) (P<0.001). Moreover, there was a positive correlation in PD patients between plasma nitrate level and age, age at disease onset, duration of disease, Hoehn and Yahr stage, and Unifi ed Parkinson’s Disease Rating Scale (UPDRS) score. However, PD patients with short disease duration did not have elevated plasma nitrate levels compared to control subjects. Conclusion: Our results argue against the hypothesis that NO is important in the development of PD in West Bengal.