We thank Professors Molimard and Moore for their interest in our article. They have some concerns regarding study design. As they are not clinicians, perhaps they are unaware that studies in severe asthma are very difficult to conduct. These patients are a major management problem and are usually excluded from conventional drug therapy trials. Any improvement in treatment would be a valuable addition to management in this difficult group of patients. Our study aimed to determine whether these patients would be better treated with either salmeterol or formoterol, and we described in the article the theoretical reasons why differences might be expected. We found that both drugs significantly increased mean morning peak flow by approximately 15 L/min above placebo. Consequently, we should have detected a similar difference in peak flow between the two drugs. However, due to the high number of patient withdrawals, the power of our study was less than originally predicted. In regard to choice of drug doses, we wished to compare the drugs at doses used in current clinical practice. Therefore, doses were chosen on this basis rather than those most likely to give a positive result. A double-blind, double-placebo design would have been preferable to the use of just one placebo. However, a matching salmeterol placebo was not available from the manufacturers. We felt it was preferable to include a single placebo rather than no placebo at all. Finally, our study has shown that, albeit not differing in efficacy, both drugs improve lung function in severe asthma and should prove useful in treatment of this difficult patient group.