Sixty patients with acute severe asthma were treated by conventional methods in all respects except for the use of steroids. Patients who were not currently taking systemic steroids (30) received none during the severe attack, and those who were currently taking systemic steroids (30) were given 400 mg hydrocortisone daily. The results were compared to a further group of 30 patients with acute severe asthma of similar severity who were treated in the same hospital by the same methods but with much larger doses of hydrocortisone (1200 mg daily). All 60 patients recovered and the time course, changes in heart rate and peak expiratory flow (PEFR) were similar in all groups. These results suggest that steroids are of doubtful value in the treatment of acute severe asthma and further randomized and controlled trials are required.