Chronic obstructive pulmonary disease (COPD) is a spectrum of smoking-related diseases that includes chronic bronchitis, emphysema, and asthmatic bronchitis. Smoking injures airways and alveoli, which invokes inflammatory processes in the respiratory tract that are mediated by oxidants, proteases, and inflammatory cytokines. Early identification of respiratory function loss and intervention are necessary to prevent progression to the disabling stages of COPD. Spirometry is a useful tool for assessing responses to smoking cessation and bronchoactive drugs. Anti-inflammatory drugs and antibiotics are useful to deal with exacerbations of bronchitis. Patient education and oxygen can improve the quality and duration of life in early and advanced stages of COPD.