Patient characteristics associated with the asthma label were investigated in 262 children, aged 8 years, who reported wheezing illness in the previous 12 months. Children were first identified by a screening questionnaire administered to the parents of all 8 year old schoolchildren in Croydon, south London. Interviews were conducted with those reported to have had a wheezing illness in the previous 12 months to obtain details of the child's illness, medical care, demographic and socioeconomic characteristics. Multivariate analysis showed that the likelihood of being labelled asthmatic was increased in those who had a parental history of hayfever [odds ratio (OR) = 2.24, 95% confidence interval (CI) = 1.22-4.14] or at least two allergic provoking factors (OR = 3.83, 95% CI = 1.44-10.15). No significant associations were found between asthma labelling and children's socioeconomic characteristics or use of general practitioner services. These findings suggest that wheeze is likely to be labelled asthma when the clinical history suggests an allergic aetiology.