The fluoroquinolones have become attractive options as treatment for a broad range of infections caused by Gram-negative bacteria. However, the value of these antibiotics to patients with infections caused by Gram-positive pathogens remains controversial. Experience with quinolones as therapy for skin and skin structure infections, osteomyelitis and peritonitis in patients receiving continuous ambulatory peritoneal dialysis suggests that the concerns which have been expressed about the use of these agents against methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis and streptococci are justified; indeed, the frequent emergence of quinolone-resistant strains of MRSA and coagulase-negative staphylococci either during or following treatment is now well documented. The fluoroquinolones should be prescribed with caution to patients with community-acquired pneumonia or whenever severe infection of pneumococcal aetiology is proven or suspected. As prophylaxis for the granulocytopenic patient, quinolones such as norfloxacin and ciprofloxacin have been shown to be effective in reducing the incidence of morbidity attributable to Gram-negative bacteria, but they have not significantly affected the incidence of infection caused by Gram-positive bacteria. In the treatment of febrile episodes in the neutropenic patient, ciprofloxacin, the quinolone investigated most extensively in this clinical setting, produced high cure rates only when it was combined with an antibiotic which was predictably active against Gram-positive organisms. We review here the role of currently-available fluoroquinolones (norfloxacin, enoxacin, pefloxacin, ofloxacin and ciprofloxacin) as treatment for these and other infections.