The objective of this research was to develop and validate analytical methods for quantitative determination of fluoroquinolones of third generation. Simple and rapid chromatographic method was developed and validated for quantitative determination of four quinolone antibiotics in tablets and injection preparations. The fluoroquinolones studied were gatifloxacin (GAT), levofloxacin (LEV), lomefloxacin (LOM) and pefloxacin (PEF). The quinolones were analyzed by using a LiChrospher 100 RP-18 column (5 microm, 125 mm x 4 mm) and a mobile phase constituted of water:acetonitrile (80:20, v/v) with 0.3% of triethylamine and pH adjusted to 3.3 with phosphoric acid. The flow rate was 1.0 mL/min and the analyses were performed using UV detector with wavelengths varying from 279 to 295 nm. The analyses were performed at room temperature (24 +/- 2 degrees C). All fluoroquinolones were separated within 5 min. The calibration curves were linear (r>or=0.9999) over a concentration range from 4.0 to 24.0 microg/mL. The relative standard deviation (R.S.D.) was < 1.0% and average recovery was above 99.54%.