Fourteen acutely ill patients admitted to the hospital with severely exacerbated asthma were randomly divided into two equal groups and treated by intravenous infusions. Group 1 received corticosteroids and group 2, corticosteroids associated with the β2-adrenergic agonist terbutaline. The effects of treatment were assessed by clinical evaluation and FEV1 measurements recorded on four consecutive days each morning before treatment, then every hour for six hours. Mean FEV1 remained statistically unchanged in group 1. In group 2, mean FEV1 showed a slight but significant improvement on the first day and then a marked increase on the second, third, and fourth days. Comparison between the two groups showed that differences in mean FEV1 were significant at the first, second, and third hours on the first day, and from the first to the sixth hour the three other days. An additional group of seven comparable asthmatic patients was treated by terbutaline alone. These subjects showed only a slight and insignificant increase in mean FEV1. This work demonstrates the necessity of combining bronchodilators and corticosteroids in the treatment of severe acute asthma and suggests the enhancement of β-adrenergic agonists by corticosteroids. © 1979, Springer-Verlag. All rights reserved.