Background: The importance of regulatory T cells (Treg) in regulating the suppression of inflammatory process in COPD have been addressed. Clinical and experimental studies have demonstrated that Treg cells immunosuppressive activity could be impaired in COPD. There are distinct Treg cells phenotypes: resting Tregs (rTregs, CD25++CD45RA+) and activated Tregs (aTregs, CD25+++CD45RA?), which, shows immunosuppressive activity, and also the cytokine-secreting T cells (FrIII, CD25++CD45RA?) with pro-inflammatory activity. Objective: To evaluate the different Treg cell phenotypes in COPD patients at different stages and non-obstructed smokers (NOS). Methods: We evaluated by flow cytometry the frequencies of Treg cell phenotypes and systemic inflammatory cytokines (IL-17, IL-10). Individuals are subset in three groups: non-obstructed smoker NOS (n=25), COPD stage I-II (n=25), and COPD stage III-IV (n=25) groups. Results: We observed an increase in the total Treg cells in the COPD III-IV group compared with NOS (p=0.03), as well as an increase in rTreg cells in both COPD groups compared with NOS (p<0.01). In contrast, aTreg cells (p=0.01) and FrIII Treg cells (p=0.01) were decreased in both COPD groups compared with NOS, whereas IL-10+CD4+ cells were increased in the COPD I-II group compared with COPD III-IV (p=0.01). The COPD I-II group showed increased ROR?t+CD4+cells (p<0.01) and IL-17+ROR?t+CD4+cells (p=0.02) compared with NOS. Conclusion: COPD individuals, since early stages, showed decreased proportion of Treg cells subpopulations with immunosuppressive activity whereas subpopulations with low immunosuppressive activity are observed increased.