Currently available fluoroquinolones have established their value in the treatment of lower respiratory tract infections due to gram-negative rods and Staphylococcus aureus. The fact that these drugs are absorbed (and well tolerated) when given orally is a major positive feature. The once daily dosage of fleroxacin [400 mg once daily intravenously (i.v.) for 2-4 days followed by oral doses of 400 mg for up to 10 days] was compared with twice daily ciprofloxacin (400 mg twice daily i.v. for 2-4 days followed by oral doses of 2 x 500 mg for up to 10 days) for treatment of inpatients with pneumonia confirmed by clinical signs and chest X ray. To date, 93 evaluable patients have been enrolled in this study. Clinical cure and improvement rates were 73.3% in the fleroxacin group and 79.2% in the ciprofloxacin group. The rate of adverse clinical or laboratory events was similar in both study groups.