To compare the perception of airway narrowing of nonasthmatic subjects with those having wheeze or mild asthma (doctor-diagnosed), the relationship between FEV1 and breathlessness was examined in 123 subjects from a general population sample. Scores for breathlessness, using the Borg scale, were recorded before and after inhaling incremental doses of methacholine to a maximal dose of 196 mcmol or a maximum change in FEV1 of 50%. A history of asthma symptoms, including wheeze in the previous 12 months, and doctor-diagnosed asthma was obtained by questionnaire. At any given level of FEV1 there was wide variation in Borg scores between subjects, however median Borg scores and the mean slope of Borg score on FEVI was greater in the asthmatic subjects or those with wheeze compared with nonasthmatic subjects or those without wheeze. In both nonasthmatic and asthmatic subjects, those with airway hyperresponsiveness had increased maximum symptom scores and maximum changes in FEVI, but similar Borg scores relative to change in FEVI, compared with those without hyperresponsiveness. We conclude that the perception of mild and moderate degrees of airway narrowing varies widely between individuals but is increased in subjects with a history of mild asthma or wheeze in the last 12 months, independently of airway responsiveness.