Leptin is one of the adipokines shown to exert a significant effect in respiratory diseases, including chronic obstructive pulmonary disease (COPD).The aim of the present study was to evaluate the possible role of serum leptin as biomarker in COPD.The serum leptin levels were assessed in 58 patents with stable COPD and 21 controls applying ELISA method.The leptin levels were higher, although not significantly, in COPD patients than in controls (221.52±24.28(SE) vs. 165.04±26.01 pg/ml, p=0.197). This tendency turned out significant when only females were compared (414.60±60.63 vs. 219.40±44.15 pg/ml, p=0.038). The levels of leptin were highly dependent on the BMI both in COPD patients (pp=0.024): they were the highest in obese individuals and decreased with reducing the BMI.In the COPD group, women had significantly higher leptin levels than men (pp=0.007) and current smokers (p=0.007). In patients with BMI above 25, several associations were observed: patients with mild COPD had higher serum leptin level than those with severe or very severe COPD (p=0.038); the leptin levels correlated positively with FEV1% (r= 0.304, p=0.045) and FEV1/FVC ratio (I= 0.348, p=0.021), and tended to correlate negatively with ABCD GOLD groups (Rho=-0.300, p=0.043) and with the CAT points (Rho=-0.258, p=0.091); the leptin levels below 300 ng/ml determined 4.08-fold higher risk for more severe COPD.The results of our study confirm that the serum leptin levels depend significantly on the BMI and are interfered by gender and smoking habits. However, this adipokine cannot be used as a serum biomarker for distinguishing COPD patients, but its decrease might be associated with aggravation of the disease.