Recurrent or chronic cough can be the symptom of a worrying condition which must be diagnosed without delay (cystic fibrosis, asthma, bronchial foreign body, bronchiectasis). Investigation of recurrent or chronic cough is based on simple principles: careful history-taking concerning the characteristics of the cough, full clinical examination to look for any associated symptoms, and auxological assessment to detect any interruption in weight increase. Only when this initial evaluation has been carried out can complementary investigations be sought. Ordinary respiratory infections that are part of the building up of immunity are predominant in coughs of children aged under 6 years and are aggravated by deleterious factors such as passive exposure to tobacco, early introduction to communal life, and urban pollution. We describe the most frequent causes of cough and their frequency according to the age of the child.