A total of 149 participants were randomized and received either montelukast(one 10 mg tablet/day) (N=71) or placebo(one tablet/day) (N=78). Spirometry was repeated at the randomization visit, and information on health status, asthma quality of life, and asthma control was collected. Participants were followed for 6 weeks after randomization. A telephone call was made at three-weeks to collect information about adverse experiences. At the final visit, participants completed spirometry, and answered questions on health status, asthma QOL and asthma control. Unscheduled health care visits for asthma during the six-week study period were noted.