Bronchodilators form the foundation of symptomatic treatment of COPD. Several long-acting bronchodilators are now available for use in COPD, but publications of large-scale studies of their efficacy have, for the most part, postdated the publication of major clinical guidelines. This article provides a critical review of large (> or =50 patients), double-blind, clinical trials of three long-acting bronchodilators in COPD (the once-daily anticholinergic tiotropium, and the twice-daily beta(2)-agonists formoterol and salmeterol) within the context of the objectives of treatment defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. Fourteen published studies were identified, of which 12 studies were published since the release of the GOLD guidelines. All three long-acting bronchodilators were found to effectively improve lung function; however, they differed in their effects on outcomes other than bronchodilation, with salmeterol demonstrating inconsistent efficacy compared with placebo in preventing exacerbations and improving health status, and only tiotropium demonstrating consistent superiority to the short-acting bronchodilator ipratropium. Based on this review, a treatment algorithm for the introduction of long-acting bronchodilators to patients with COPD is proposed, which includes the use of long-acting bronchodilators early in the treatment algorithm.