Fluoroquinolones represent a major advance in antimicrobial chemotherapy. Currently, there are five fluoroquinolones approved by the FDA, and many more quinolones are expected to become available in years to come. Although their clinical utility is constantly expanding, they have been best studied in complicated urinary tract infections, chronic osteomyelitis caused by gram-negative bacilli, bacterial gastrointestinal infections such as traveler's diarrhea and typhoid fever, and uncomplicated gonococcal infections and in the prophylaxis of bacterial infections in patients with neutropenia. These agents have the convenience of oral administration, favorable pharmacokinetic properties, and low toxicity profiles but should be used advisedly because indiscriminate use may result in the early emergence of resistance.