Forty-nine nonsteroid-dependent children hospitalized with status asthmaticus were randomized to receive IV placebo or methylprednisolone treatment (1 mg/kg every six hours). All patients received nebulized isoetharine inhalations and continuous IV aminophylline infusion. Twenty-four hours after admission, the methylprednisolone-treated patients demonstrated a greater rate of improvement in their clinical scoring index than did placebo-treated children. However, the duration of hospital stay was not significantly shortened. Twenty-eight of the patients performed serial bedside spirometry at 0, 12, 24, and 36 hours after admission. The methyl-prednisolone-treated patients experienced a more rapid recovery from peripheral airway obstruction as measured by forced expiratory flow rate during 25% to 75% of forced vital capacity (FEF25-75). The magnitude and rate of improvement in FEF25-75 was significantly greater at 36 hours (P less than .05) and independent of changes in peak expiratory flow rate, forced vital capacity, or forced expiratory volume in the first second of forced vital capacity. Placebo-treated patients had a higher incidence of asthma relapse within 4 weeks of discharge (eight v two relapses, P less than .05). Findings of this study indicate that IV corticosteroid therapy is beneficial in treating pediatric status asthmaticus.