The Salmeterol and Leukotriene Modifiers versus ICS Treatment (SLIMSIT) study initiated recruitment in September 2002. The goal was to randomize 180 participants. SLIMSIT was a 36-week, double-blind, placebo-controlled, cross-over study, with time to treatment failure as the primary endpoint. Prior to each double-blind treatment phase, participants underwent a 4-week run-in period with combined inhaled beclomethasone HFA and the leukotriene receptor antagonist (LTRA) montelukast. This was followed by 14 weeks of double-blind treatment. During the initial 4-week run-in period, participants who met National Asthma Education Program criteria for moderate persistent asthma received a controller regimen to obtain baseline information on symptoms, beta-agonist use, and PEF for use in defining treatment failure for each participant over the duration of the study. The final visit of this run-in period served as the baseline of comparison for the study variables measured during the initial treatment phase. At the end of the initial run-in, participants with stable asthma symptoms were randomized to one of the following two treatment regimens for 14 weeks: 1) daily oral placebo, twice daily inhalation of salmeterol 50 mg by dry powder inhaler (DPI), and twice daily inhalation of beclomethasone HFA 80 mg by MDI; or 2) once daily oral montelukast 10 mg, twice daily inhalation of salmeterol 50 mg by DPI, and twice daily inhalation of placebo. Active beclomethasone HFA and the beclomethasone HFA placebo were given via a MDI delivery device, while salmeterol was given by a DPI Diskusâ. A computer interface randomized participants into the two treatment groups, stratifying by clinical center and FEV1 at the randomization visit (less than 80% versus greater than 80% of predicted FEV1). During the first treatment period, participants made three visits to the clinic over 14 weeks. These visits included re-assessment of the study variables and careful monitoring for increasing asthma symptoms and potential treatment failure. Subsequently, participants entered a second run-in period in which they received single-blind treatment with inhaled beclomethasone HFA and oral montelukast as in the first run-in period. At the end of the second run-in period, participants crossed over to the alternate treatment regimen for the second 14-week treatment phase, which included three visits to the clinic. These visits again included re-assessment of the study variables and careful monitoring for increasing asthma symptoms and potential treatment failure. DSMB recommended termination of the study prior to target enrollment because sufficient data about the primary outcome had been obtained. SLIMSIT results were presented at the May 2005 American Thoracic Society Annual Meeting. The data are under analysis for subsequent publication.