Summary. The study was aimed at investigation of regulatory T-lymphocytes (Treg) with CD4+CD25+CD127 phenotype in non-smoking and smoking patients with chronic obstructive pulmonary disease (COPD). We examined 21 non-smokers with COPD, 20 smokers with COPD, 20 healthy non-smokers, and 21 healthy smokers. T-lymphocyte subtypes were analyzed using flow cytometry. Treg percentage was significantly higher in non-smokers with COPD compared to non-smoking healthy controls. Blood Treg number in smokers with COPD was higher than in healthy smokers. Smokers with COPD had significantly higher proportion of Treg than non- smokers with COPD. We also found significant inverse correlation between Treg proportion and the CD8+ T-lymphocyte percentage in non-smoking COPD patients. The results of this study suppose a possible contribution of Treg to the systemic inflammation in COPD irrespectively of smoking.