The asthma severity index (ASI) is proposed as a tool to monitor the course of patients with increased risk of asthma-related morbidity and mortality. The ASI is a weighted summary of the diagnostic features of potentially fatal asthma (PFA). Fifteen patients with PFA were evaluated with ASIs calculated for the intervals 1 year prior to and 1 year following management by our allergy-immunology service. In each patient, a reduction was noted in the ASI following management, which corresponded to a reduction in asthma events. The ASI will have utility in the evaluation of chronic asthma treatment and in patient education.