We report a case of Legionella bozemanii pneumonia that failed to respond clinically and microbiologically to erythromycin administration. The organism was recovered from bronchial brushings and washings and was demonstrated to be sensitive in vitro to erythromycin as well as to rifampin and sulfamethoxazole-trimethoprim. The patient received a 9-day course of erythromycin before she died. Nonetheless, postmortem lung tissue yielded Legionella bozemanii. In treating Legionella pneumonia unresponsive to erythromycin, addition of another antibiotic, based on sensitivity testing, should be considered.