The Beta Agonist Response by Genotype (BARGE) study was reviewed by the Protocol Review Committee in December 1998. Recruitment started in September 1999. BARGE was a 54-week randomized, double-blind, crossover study comparing the effects of regularly scheduled use of inhaled albuterol (2 puffs four times a day) to placebo. Two groups of 36 participants each included individuals who had mild to moderate asthma and who differed by their genotype at the codon for the 16th amino acid of the B2-adrenergic receptor. A total of 36 participants harbored the B16-Arg/Arg genotype and the other 36 harbored the B16-Gly/Gly genotype at the B2-adrenergic receptor. Qualified participants entered a 6-week single-blind run-in period during which they were treated with an inhaled placebo (2 puffs 4 times a day) and given inhaled ipratropium bromide for use as a rescue medication. Asthma control was characterized by AM PEF, spirometric values, AM/PM PEF variability index, asthma symptoms, quality of life, use of rescue medications, and occurrence of events of adverse asthma control. Baseline data were obtained on airway responsiveness, the protective effect of albuterol against methacholine-induced bronchoconstriction, the maximum bronchodilator effect of albuterol, and exhaled nitric oxide. Participants were then randomized to a 16-week double-blind treatment phase in which they received either inhaled albuterol or placebo (two puffs 4 times a day). Asthma control was monitored by the above indicators during this time. At the end of the blinded treatment period, all participants were returned to single-blind regular use of a placebo inhaler (2 puffs 4 times a day) for an 8-week run-out period. Following cross-over to double-blinded treatment with albuterol or placebo, the 8-week run-out period also served as the run-in period for the second stage of the study. Asthma control was monitored by the same indicators as in the first stage. At the end of the second blinded treatment period, all participants were returned to single-blind regular use of a placebo inhaler (2 puffs 4 times a day) for an 8-week run-out period. During the entire study, participants used inhaled ipratropium bromide as rescue medication to avoid the confounding effects of B2-adrenergic stimulation on the outcome variables to be monitored. In the event that an episode of adverse asthma control responded incompletely to ipratropium, albuterol was used as a superseding rescue medication. Comparisons of asthma control, within each genotypic group during periods of randomized treatment, were assessed as the difference in the change in outcome variables between the end of Stage 1 randomized treatment and the end of Stage 1 run-in, and between the end of Stage 2 randomized treatment and the end of Stage 1 run-out. The study was completed and results have been published.