Asthma pathogenesis appears to be a result of a complex mixture of genetic and environmental influences. There is evidence that Mycoplasma pneumoniae and Chlamydia pneumoniae play a role in promoting airway inflammation that could contribute to the onset and clinical course of asthma. If antimicrobial therapy can eradicate these organisms, it might be possible to alter the course of the disease. Although antibiotics have no role in the routine management of acute exacerbations of asthma, certain macrolide antibiotics have been shown to have anti-inflammatory activity. Part of this effect is due to their known inhibition of steroid and theophylline metabolism, but through a myriad of mechanisms that are incompletely understood, macrolide antibiotics have additional broad anti-inflammatory properties that might prove useful in the management of asthma and other inflammatory diseases.