There is a reason to suspect that pediatric OSA due to ATH could be treated by a short course of systemic steroids. For instance, steroids can reduce tonsillar size in infectious mononucleosis. We therefore performed assessments of symptomatology, ATH, and OSA severity before and after a 5 day course of 1 mg/kg/day of oral prednisone in 9 children (6 girls). Selection criteria included age 1-11 years, a mixed/obstructive apnea/hypopnea index (MOAHI) of≥ 3/hr, ATH, symptoms suggesting OSA, and intent to perform adenotonsillectomy. Before and after steroid treatment, physical and radiographic exams documented ATH, and home polysomnography (Ped Pul 20:241-52, 1995) and a questionnaire based OSA score (J. Ped. 105:10-14, 1984) documented severity of OSA. RESULTS. Only one child showed enough improvement to avoid operation. Clinical symptomatology did not improve after steroid treatment but did after removal of tonsils and/or adenoids: OSA score (x± SD), 1.8 ± 2.2 vs 1.5 ± 2.2 vs -2.7 ± 1.6, p<.01. Polysomnographic indices of OSA severity did not improve after steroid treatment: MOAHI, 13.9 ± 15.2 vs 9.9 ± 7.1, p=0.29. Tonsillar size decreased in only two patients; adenoid size was marginally reduced after steroids: adenoid/nasopharyngeal ratio,.69 ±.10 vs.63±.09, p=.05. CONCLUSIONS. These results suggest that a larger, double-blind placebo controlled trial of systemic corticosteroids is not warranted. However, recent data (Peds 95:355-64, 1995) suggest that a longer course of nasal steroids might reduce adenoidal size, improve symptomatology, and decrease OSA severity. Support: The Hospital for Sick Children Foundation.