The in-vitro activity of temafloxacin compared with other quinolone antibiotics was evaluated using 579 bacterial strains and three isolates ofChlamydia trachomatis. The MICs of temafloxacin for 90%ofHaemophilia influenzae, Neisseriaspp., Enterobacteriaceae,Bacteroides fragilisandCh. trachomatiswere all≤1 mg/l, an activity comparable with or superior to that of ofloxacin and superior to those of fleroxacin and norfloxacin. Temafloxacin, although more active against anaerobes, was in general slightly less active than ciprofloxacin. AgainstStreptococcus pneumoniaeandStaphylococcus aureus(including MRS A) temafloxacin was twice as active as ciprofloxacin. The pharmacokinetics of temafloxacin were studied in six volunteers, following a single 400 mg oral dose, measuring concentrations in plasma, inflammatory fluid and urine. Mean peak plasma levels of 3·3 mg/l were achieved. The mean plasma elimination half life was 6·8 h and the percentage penetration into blister fluid was 104·5%. Of the administered dose 51·8%was excreted in urine by 26 h. Serum and blister fluid levels in excess of 1 mg/l were present for at least 8 h post dose, suggesting that a once or twice daily dosing regimen would be suitable for the treatment of infections caused by susceptible orga