Clinical symptoms are often used as a measure in asthma management, but a variety of symptoms and scales are available. The objectives of this systematic review were as follows: (a) to present correlations between symptoms and measures of airway calibre; (b) to present the scoring systems/ scales used in the publications. In the review, more than 10 000 publications were found under the key words: asthma and symptom(s). Twenty-one remained when FEV1/PEF, scale/score and correlation were added as key words. In summary, no standardized method exists for measuring asthma symptoms with respect to severity. This is the case for both the symptoms and the scales. There are two recently-developed asthma-control scales available (one of which has not yet been published and is not included in the review).