Gastro-oesophageal reflux (GER) is more frequent in asthmatic patients than in the community at large. A causative association between the two diseases is suspected. Twenty-four hour ambulatory intraoesophageal pH monitoring represents the golden standard for the diagnosis of GER. The medical and/or surgical treatment of reflux in asthmatic patients with GER can improve pulmonary symptoms and to a lesser extent pulmonary function. The selection of the patients who will benefit from a GER treatment is difficult. Some symptoms like intrinsic asthma, nocturnal crises, could predict a good response to GER treatment.