The aim of the present study was to quantify the healthcare utilization of a child population according to level of respiratory illness. A stratified random sample of 713 children was selected from respondents to a postal respiratory questionnaire, carried out in two general practice populations in 1993. Children were stratified into four groups according to the number of positive responses to five key questions. These groups were used as indicators of likelihood of asthma diagnosis. A search was made of these childrens' practice records covering a 2-yr period, to include both primary and secondary healthcare. There was a significant increase across positive response groups in the proportion of children having primary and secondary care based consultations, particularly for respiratory conditions (p=0.001). There was also a significant increase in prescribing. Of those children considered to be "likely asthmatics" from their questionnaire responses, 8.1% (n=31) did not receive any primary or secondary care for a respiratory problem over the 2-yr period. As the likelihood of respiratory illness increased in this population, more demand was made upon resources for the treatment of respiratory illness. Quantification of this demand enables evidence based resource allocation decisions to be made. This method of quantification could be applied in other populations.