Abstract The objective of this study was to compare the efficacy and safety of triamcinolone acetonide hydrofluoroalkane 134a (HFA) (chlorofluorocarbon [CFC] free) with those of triamcinolone acetonide P-12 (CFC containing) in children with chronic asthma. This multicenter, randomized, double-blind, parallel-group study comprised 473 children (6 to 13 years of age) with asthma. Patients received 12 weeks of treatment with 150, 300 or 600 μg of triamcinolone acetonide HFA daily given as 1, 2, or 4 puffs (75 μg/puff) or the same doses of triamcinolone acetonide P-12 after a 3- to 28-day baseline period. Mean percent change in forced expiratory volume in 1 second was 12.17% to 22.02% with HFA and 13.53% to 22.62% with P-12. Albuterol use decreased by 2, 2.7, and 3.6 puffs/d with the HFA 150-, 300-, and 600-μg groups, respectively, and by 2.2, 2.4, and 3 puffs/d for the respective P-12 groups. Significant improvement ( P<0.05) in symptoms was noted with both formulations. Overall, both formulations were similarly effective in improving pulmonary function and relieving asthma symptoms, and in general, both formulations were more effective at the higher doses of triamcinolone acetonide. Both formulations were well tolerated. Based on these results, we concluded that triamcinolone acetonide HFA inhalation aerosol is safe and effective in children with asthma and produces effects on pulmonary function and asthma symptoms similar to those produced by triamcinolone acetonide P-12.