The present randomized, double-blind placebo-controlled study aimed at investigating the possible improvement in endurance performance caused by inhaled salmeterol (long-acting beta 2-agonist) and salbutamol (short-acting) compared to placebo in 18 healthy well-trained athletes, aged 17-30 years old. Lung function (flow-volume loops) was measured before and after each inhaled study drug and after run to exhaustion. After inhalation of study drug and 10 min warm-up, anaerobic threshold was measured; thereafter maximum oxygen uptake, peak ventilation and running time until exhaustion during a brief graded exercise were measured. No significant differences were found for ventilation, oxygen uptake or heart rate at anaerobic threshold or at maximum performance between placebo and the beta 2-agonists. Lung function increased significantly after exercise, but without differences between the beta 2-agonists and placebo. Running time till exhaustion was significantly reduced after both the long- and the short-acting beta 2-agonist compared to the placebo.