Both in terms of morbidity and mortality, the therapeutic and organizational management of asthma pose a considerable and continuing challenge to healthcare delivery. One element in attempts to meet this challenge is the recognition of appropriate outcome measures to assess progress in tackling the burden of this disease. This study therefore aimed to assess pragmatically the effectiveness of a revised asthma morbidity index in identifying varying patterns of morbidity in U.K. general practices. A postal survey was conducted of 2,762 patients believed to have or have had asthma from the lists of 12 general practices within the Eden Valley in Cumbria, using a questionnaire which combined the revised Jones morbidity index with questions on age, medication and perception of current asthma. Prescribing data were also recovered for 11 of the practices for the quarter within which the postal survey was conducted. Responses were obtained from 2,123 subjects (77%), of whom 1,474 (70%) believed themselves to be currently asthmatic. In this group, 18% reported low morbidity 34% medium morbidity and 48% high morbidity Age and inhaled steroid use were both positively and significantly associated with high morbidity. Those taking inhaled steroids were 1.4 times more likely to report high morbidity than those nottaking steroids. The prescribed corticosteroid/bronchodilator ratio for cost was both negatively and significantly associated with high morbidity. The revised morbidity index is a simple tool of use in the surveillance of asthma in primary care. It identifies spectra of morbidity which vary between practices, which may be of use in assessing the quality of asthma care provided in the community.