Objectives. To investigate leptin levels and their relationship to body composition and demographic and clinical characteristics of Turkish patients with Parkinson's disease (PD). Patients and Methods. Forty eligible PD patients and 25 healthy controls were included in the study. Body composition measurements (height, weight, waist circumference (WC), and body mass index (BMI)) of the whole sample and clinical findings of PD patients were evaluated in the on-state. A single 5mL fasting blood sample was obtained from each participant in the morning. Severity of PD was evaluated using the Hoehn and Yahr scale and the Unified Parkinson's Disease Rating Scale. Results. The mean age of the patients and controls was 60.8 +/- 9.4 and 61.8 +/- 5.8 years, while the mean BMI was 30.17 +/- 5.10 and 28.03 +/- 3.23 and the mean leptin levels were 6.8 +/- 6.9 and 3.9 +/- 3.8 ng/mL, respectively. Only age and gender were correlated with leptin levels. There was a significant difference (P < 0.001) in leptin levels between male (3.6 +/- 3.1 ng/mL) and female (14.3 +/- 7.7 ng/mL)PD patients. Among the male PD patients, older age and higher BMI and WC values were associated with higher mean leptin levels. There was not any significant relationship between leptin levels and clinical findings in PD patients. Conclusion. These results may suggest that leptin levels have no determinative role in the follow- up of PD patients with regard to the severity and clinical prognosis of PD.