Chronic obstructive pulmonary disease represents a complex syndrome including chronic bronchitis, pulmonary emphysema and chronic asthma, characterised by persistent airway obstruction with different degree of reversibility. Clinical manifestations depend on the relative contribution of these different diseases in the single patient. Relationship between symptoms and severity (as expressed by forced expiratory volume in one second) is weak, and chronic airway obstruction generally precedes symptoms. Cough, sputum, wheezing, and dyspnea are the main symptoms of chronic obstructive pulmonary disease, and they must be carefully inquired and quantified. Symptoms and signs of chronic obstructive pulmonary disease depend on the type of disease (chronic bronchitis or emphysema), and also on the complications and comorbidities. Accurate definition of the heterogeneity of chronic obstructive pulmonary disease can be useful in the prognosis and management of the disease.