In a double-blind, 12-week study of corticosteroid-dependent reversible bronchial asthma, 20 of 31 (64.5%) patients receiving triamcinolone acetonide aerosol, 800 microgram daily, were able to discontinue oral steroid therapy. This compares with three of 29 (10.3%) treated with aerosol placebo. At the end of the 12-week period, the mean 8 AM plasma cortisol level had increased from 5.3 +/- 4.1 to 8.6 +/- 5.2 microgram/dl in those receiving triamcinolone acetonide. The mean percent predicted values in the triamcinolone group for forced expiratory volume in the first second rose from 44.8 to 62.4 at two weeks (P less than .005), for forced vital capacity from 64.1 to 79.9 (P less than .005), and for maximum midexpiratory flow rate from 26.7 to 46.7 (P less than .005). The improved pulmonary function values persisted while the oral prednisone equivalent daily dose decreased from a mean of 13.3 to 2.9 mg at 12 weeks. Significant oral candidiasis was detected in two patients. Aerosol triamcinolone acetonide appears to be an effective alternative to beclomethasone dipropionate for use in patients with bronchial asthma.