We evaluated the effect of inhaled indomethacin, a nonsteroidal antiinflammatory drug (NSAID), on exercise-induced bronchoconstriction (EIB) in children with asthma. Nine asthmatic children (7 boys, 2 girls, with a mean +/- SEM age of 11.0 +/- 0.8 yr) with a history of EIB participated in this study. These subjects were pretreated with inhaled indomethacin (3 mg/m2 body surface area [BSA]) or placebo (0.9% saline) according to a double-blind, randomized, crossover design, and underwent an exercise challenge test 15 min after the pretreatment. Inhaled indomethacin significantly attenuated EIB. The mean maximal percent decrease in FEV1 following exercise was 36.1 +/- 5.7% after placebo and 18.0 +/- 4.6% after indomethacin pretreatment (p = 0.0310). Indomethacin also significantly reduced the mean maximal decrease in arterial oxygen saturation after exercise (p = 0.0378). The inhibition of local prostaglandin synthesis and/or ion transport in the airways may be a mechanism involved in the protective potency of inhaled indomethacin.