Corticosteroids continue to be used by many physicians to treat infants with bronchiolitis. The aim of this study was to examine the short-term and long-term efficacy of oral corticosteroid therapy when added to beta2-agonists in infants with mild to moderate bronchiolitis (defined as the first episode of wheezing associated with low grade fever, rhinitis, tachypnea, and increased respiratory effort in a previously healthy infant during the winter months). Infants with mild to moderate bronchiolitis, were randomly assigned to receive either oral prednisone (2 mg/kg/day) or placebo for 3 days. All patients received nebulized albuterol q.i.d. during this period. Upon admission and after 3 days of therapy, a clinical score was assigned based on respiratory rate, use of accessory muscle, and the presence of wheeze. Oxygen saturation (SaO2) was also measured. On day 7, we inquired as to the well-being of each child. Two years later, the development of chronic respiratory symptoms was assessed. Thirty-eight infants were enrolled in the study; 20 received prednisone and 18 received placebo. Both groups were similar in terms of age, duration of illness prior to enrollment, pretrial medication use, clinical severity of bronchiolitis, history of atopy, and family history of atopy. After 3 and 7 days of treatment, both groups showed similar clinical improvement and there were no statistically significant differences between the two groups in the clinical score or in the SaO2. No major side effects were observed. Two years later, 32% of the infants continued to suffer from chronic respiratory symptoms, with a similar prevalence in both groups. We conclude that a 3-day course of oral corticosteroids is of no benefit to infants with mild to moderate bronchiolitis who are also treated with an inhaled beta2-agonist.