Antibiotics can be aerosolized to the lower respiratory tract of patients with pulmonary infections. With attention to stability of the antibiotic, its ability to be aerosolized, and particle size of the aerosol, rational design of an antibiotic aerosol treatment regimen is possible. The choice of nebulizer for aerosol antibiotic administration depends not only on drug stability under the nebulization conditions, but practical considerations such as ease of use in the home and expense. In general, a greater volume of respirable aerosol is generated by an ultrasonic device in comparison to the jet nebulizers. Of the factors affecting antibiotic delivery to the lower respiratory tract, the patients and their disease are the most important. This patient effect is not directly amenable to medical intervention, but can be controlled through measurement of antibiotic concentrations in respiratory secretions, seeking a target estimated from the best available in vitro data.