It is one of the most common causes of chronic cough in children, with cough as the only or main manifestation, without significant wheezing. Diagnosis is based on: (1) cough lasting >4 weeks, often with episodes or exacerbations at night and/or early morning, with a predominantly dry cough; (2) no clinical signs of infection or ineffective with prolonged antibiotic therapy; (3) effective diagnostic treatment with anti-asthmatic drugs; (4) exclusion of other causes of chronic cough; (5) positive bronchial excitation test and/or daily variability of PEF (continuous monitoring for l to 2 weeks ) ≥ 20%; (6) personal or first- or second-degree relative special.