SUMMARY. The need for new, more effective antituberculous drugs is pressing. The treatment of active disease needs to be shortened and simplified, the treatment given for latent tuberculosis (TB) also needs to be shortened and, most importantly, improved therapy for multi-drug resistant TB (MDR-TB) is needed. The fluoroquinolones are the first novel drugs since the rifamycins found to exert significant activity against M. tuberculosis. They are currently being used for the prophylactic treatment of individuals who have been exposed to MDR-TB, for the treatment of MDR-TB, for empirical treatment of TB in areas with high rates of MDR-TB and for patients who present severe adverse reactions to the conventional antituberculous regime. Conversely, their use is not recommended as a first-line drug for the routine treatment of TB. Fluoroquinolones are relatively safe antimicrobial compounds that bind to bacterial topoisomerases, resulting in cell death. They show strong bactericidal activity both in vitro and in vivo, and some, such as moxifloxacin, also exert sterilizing activity. Resistance to fluoroquinolones, associated with their previous use, is a significant issue. The emergence of resistance is far more likely when ciprofloxacin is included in the regime. In the case of community-acquired pneumonia the decision to administer a fluoroquinolone should be made with caution and the possibility of pulmonary TB should be considered. The appropriate use of fluoroquinolones both in the treatment of TB and for community-acquired pneumonia is of critical importance, since the emergence of resistance is becoming a significant problem. Pneumon 2008; 21(4):–