Steady-state pharmacokinetics of oral fleroxacin were studied in six males who had skin or skin structure infections and who were receiving 400 mg of fleroxacin once a day. Blood samples (n = 10) and total urine output were collected during a 24-h dosing interval. Fleroxacin concentrations in serum and urine were determined by high-performance liquid chromatography. The maximum concentration in serum and the time to achieve that maximum were 6.2 ± 2.2 μg/ml and 0.94 ± 0.62 h, respectively. The absorption half-life, alpha half-life, beta half-life, apparent steady-state volume of distribution, apparent total body clearance, and renal clearance were 0.56 ± 0.37 h, 0.78 ± 0.51 h, 10.56 ± 1.40 h, 0.85 ± 0.31 liters/kg, 129.2 ± 19.6 ml/min, and 53.3 ± 16.7 ml/min, respectively. Fleroxacin disposition in this patient population was similar to that in noninfected volunteers with normal renal function.