Asthma severity can be judged by measurements of symptoms, lung function, and medication requirements. The objective was to compare the effect of a 4-wk monotherapy with low-dose triamcinolone, montelukast and nedocromil on asthma control, lung function, eosinophil blood count, and bronchial hyper-reactivity in children with mild to moderate asthma allergic to dust mite. Two hundred fifty-six children, aged 6-18 yr, with mild to moderate asthma, participated in an 8-wk study. This was a three-arm, randomized no blinding or placebo pragmatic trial comparing the effect of triamcinolone acetonide (400 microg/day), inhaled nedocromil and montelukast sodium on clinical parameters of asthma [score, forced expiratory volume in 1 s (FEV(1))], PC20H, and eosinophil blood count. Two hundred forty-six children completed the study. After 4 wk of treatment with triamcinolone and montelukast, FEV(1) and PC20H significantly increased, and mean total symptoms score and mean number of eosinophil count in serum significantly decreased. Triamcinolone had a stronger effect on PC20H than montelukast. Nedocromil improved total asthma symptoms score and lung function. There was a reduction in the daytime and night-time symptom scores after treatment with all three drugs. Triamcinolone and montelukast had a stronger effect on asthma symptoms than nedocromil. There were statistically significant differences in reduction of nocturnal asthma symptoms between the triamcinolone and nedocromil groups (p < 0.001) and between montelukast and nedocromil (p = 0.001) groups, but not between the triamcinolone and montelukast groups. There was a reduction in beta-agonists use after treatment with all three drugs, with the strongest effect of triamcinolone. The study showed the strongest effect of low-dose inhaled steroids on clinical symptoms, lung function, bronchial hyper-reactivity and eosinophil blood count when compared to other asthma medications.