Moxifloxacin is a novel 8-methoxyquinolone with enhanced potency against important Gram-positive pathogens, notably Streptococcus pneumoniae. It retains class activity against Gram-negative bacteria. Currently available for oral use, it has a prolonged half-life, enabling once-daily administration and reflecting balanced renal and hepatic elimination. Clinical trials have demonstrated an excellent safety record with minor class effects in the skin and gastrointestinal systems. Potential for phototoxicity is minimal and moxifloxacin is free of clinically significant neurological, hepatic or cardiac effects. Investigated primarily in respiratory infections, moxifloxacin has shown excellent performance in community-acquired pneumonia (both pneumococcal and atypical), acute exacerbations of chronic bronchitis and acute maxillary sinusitis. It is available in many European countries and in the US where it is rapidly establishing clinical acceptance and formulary inclusion.