Legionellosis or Legionnaires’ disease (LD) is a common cause of community-acquired pneumonia and can cause rapidly progressive respiratory failure and septic shock. Respiratory symptoms generally predominate; nonspecific symptoms include fever, malaise, myalgias, anorexia, and headache. There are no characteristic presenting clinical or radiological features, and the severity of illness can range from mild to severe. Although erythromycin was initially used to treat LD, trials have demonstrated that the newer macrolides and the respiratory fluoroquinolones are the antimicrobial agents of choice. Given the potential for outbreaks of LD, documented cases should be reported to the local or state health department. Along with LD, Legionella may cause Pontiac Fever, an influenza-like illness without pneumonia, which is self-limiting and does not require treatment.