We conducted a prospective, randomized, placebo-controlled, double-blind study to determine if the leukotriene inhibitor montelukast is effective in eliminating persistent middle ear drainage in patients with otitis media with effusion (OME). Our study population was made up of patients aged 2 to 6 years who had had confirmed OME in one or both ears for at least 2 months. Patients were randomized to receive either placebo or 4 mg of montelukast daily for 1 month. The main outcome measure was clearance of middle ear effusion as demonstrated by otoscopy and tympanometry 1 month after the initiation of treatment. Our goal was to recruit 120 patients; however, an interim analysis was conducted after 38 patients had completed their regimen (19 patients in each group) when it became apparent that montelukast was not having any effect in clearing the effusions. Indeed, the OME had cleared in only 3 montelukast patients (15.8%) and 4 controls (21.1%); the difference was not statistically significant (p > 0.90). Based on this early trend, the study was terminated at this point. We conclude that montelukast appears to be no more effective than placebo in eliminating persistent middle ear effusion.