Chronic obstructive pulmonary disease (COPD) is characterised by an excessive inflammatory response to inhaled particles, mostly tobacco smoking. Although inflammation is present in all smokers, only a percentage of them develop COPD. T-lymphocytes are important effector and regulatory cells that participate actively in the inflammatory response of COPD. They comprise the T-cell receptor (TCR)-alpha beta (CD4+ and CD8+) and TCR-gamma delta T-lymphocytes. The latter represent a small percentage of the total T-cell population, but play a key role in tissue repair and mucosal homeostasis. To investigate TCR-alpha beta (CD4+ and CD8+) and TCR-gamma delta T-lymphocytes in COPD, the present authors determined, by flow cytometry, the distribution of both subpopulations in peripheral blood and bronchoalveolar lavage (BAL) samples obtained from patients with COPD, smokers with normal lung function and never-smokers. The present study found that: 1) the distribution of CD4+ and CD8+ lymphocytes in blood and BAL was similar in all three groups; 2) compared with nonsmokers, gamma delta T-lymphocytes were significantly increased in smokers with preserved lung function; and 3) this response was blunted in patients with COPD. These results highlight a novel, potentially relevant, pathogenic mechanism in chronic obstructive pulmonary disease.