The authors review the now well-established data that concerns the relationship between asthma and gastro-oesophageal reflux (GER). These include the high frequency of the association in severe asthma, the diagnostic procedure of GER in asthmatics and the significance of reflux in these patients (reflux that causes asthma or reflux that is secondary to asthma). Then the mechanism of the action of GER on asthma are discussed. In the second part the authors summarise the following issues, that are only partly resolved. Evaluation of the possible worsening effect of GER on the symptoms of asthma. They insist in particular on the valuable contribution of clinical data and the results of the Bernstein acid infusion test. Therapeutic indications, particularly those for surgical correction. Recent results from a long term study of surgical treatment of 46 patients are presented.