Although utility of β-lactams in the treatment of legionnaire’s disease could not be demonstrated, clinical cures of human legionellosis with imipenem have been reported. We report the case of a 45-year-old man who presented clinical and radiological features of ‘typical’ bacterial pneumonia. He was successfully treated with imipenem. Serologic studies showed seroconversion for Legionella pneumophila. Although several (3-lactam antibiotics have shown a high activity against Legionella pneumophila in vitro, their clinical utility has not been demonstrated . We report a case of legionnaire’s disease (LD) associated with acute respiratory distress syndrome (ARDS) which was successfully treated with imipenem.