The discomfort caused by persistent cough compels a great number of patients to seek medical aid. Persistent cough interferes with the patient's sleep, professional and social activities. The pathogenic triad of asthma, post nasal drip syndrome and gastroesophageal reflux disease, alone or in combination, is responsible for the majority of cases of chronic cough. Investigation of chronic cough, according to a rational protocol leads to the identification of the cause for chronic cough in approximately 90% of the cases.