The authors comment on Dr. Murray Krahn and associates' findings on the direct and indirect costs of asthma in Canada in 1990 (see pages 821 to 831 of this issue). They believe this study is the most meticulous of recent cost-of-illness analyses of the economic burden of asthma. They argue that although Krahn and associates' study is a useful addition to the economic literature on this common disorder, the cost-of-illness method of analysis cannot address the question of the relative costs and benefits of specific interventions. The next task in improving the management of asthma is therefore to undertake studies that will allow clinical and administrative decision-makers to assess the relative cost-effectiveness of a range of available treatments.