A complicating factor in the history of asthma animal research has been the scientific community's willingness to measure PenH as a surrogate for airway responsiveness. This method, now known to be flawed (15), was easily applied and hence readily accepted in this era when our physiologic expertise is poor and expediency required. We now must reevaluate many published and accepted concepts that were based on this technique. Accurate, invasive physiologic testing in mice is essential and achievable. However, it will require our reinvestment in physiology education and research.