Efficacy and safety of alternate-day prednisolone compared to single daily cloprednol were evaluated over a six-week period in 11 children with severe asthma requiring in-residence medical supervision and long-term corticosteroid therapy. Clinical indices of efficacy, including daily pulmonary symptom scores, number of asthma attacks, asthma severity scores, and bronchodilator usage, all favored cloprednol. Afternoon pulmonary function tests (FEV1, FVC, and PEFR) were all significantly improved during the cloprednol period. Although plasma cortisol values remained within the broad range of normal during the cloprednol period, mean values were consistent with partial pituitary-adrenal suppression similar in degree to that observed 24 hours after administration of an alternate-day program of prednisolone therapy. The results of this trial showed cloprednol in single daily doses to be more effective than prednisolone in alternate doses for the treatment of children with severe asthma.