Background: Current guidelines advocate the, use of preventative anti-inflammatory therapy for mild persistent asthma. Objective: We compared the efficacy and anti-inflammatory profiles of a leukotriene receptor antagonist and a low dose of inhaled corticosteroid in patients with mild persistent asthma. Methods. Twenty-one adult Patients with mild asthma received 4 weeks of either once-daily inhaled hydrofluoroalkane triamcinolone acetonide (450 mug/day ex-actuator dose) or oral mon- telukast (10 mg/day) in a randomized, placebo-controlled, single-blinded crossover study. Measurements were made before and after 2 and 4 weeks of each treatment. Results: At the endpoint (after 4 weeks), triamcinolone and montelukast had improved the primary outcome (provocative dose of methacholine required to produce a 20 % fall in FEV1) in comparison with placebo (P <.05), there being no difference between the treatments (1.09-fold; 95% CI 0.73 to 1.63). Triamcinolone was better than placebo or montelukast for effects on all other surrogate inflammatory markers (P <.05), including exhaled nitric oxide, blood eosinophils, serum eosinophil cationic protein, plasma intracellular circulating adhesion molecule 1, and plasma E-selectin. Both treatments improved (P <.05) morning and evening peak flow, nighttime. beta2-agonist use, and symptoms in comparison with placebo, though triamcinolone was better than montelukast (P <.05) with regard to peak flow. Triamcinolone produced suppression (P <.05), of overnight urinary cortisol/creatinine and serum osteocalcin. Conclusion: Once-daily inhaled corticosteroid and leukotriene antagonist improved the primary outcome variable of bronchial hyperresponsiveness to a similar degree.