beta 2-Adrenergic agonists are widely prescribed for the symptomatic relief of asthma, but are not thought to alter the underlying pathogenesis. However, it has been suggested that salmeterol, a new beta-agonist with prolonged bronchodilatory action, may have anti-inflammatory properties. A double-blind crossover study of 4 weeks of inhaled salmeterol versus placebo was performed using a chemiluminescence assay to measure peripheral phagocyte function before and after each treatment period. Circulating cytokines [interleukin-1 beta (IL1 beta), IL4, IL6, IL2 receptor (IL2R)] were also measured. Although salmeterol caused a significant improvement in spirometry, there was no apparent modulation of phagocyte or cytokine activity. No evidence was obtained to support a clinically significant anti-inflammatory action of salmeterol.