Thirty-nine patients with uncomplicated gonorrhea were randomized to receive single, oral 50-, 100-, or 200-mg doses of trovafloxacin (CP-99,219), a new quinolone antibiotic. All 31 evaluable patients were cured of infection. Trovafloxacin was well tolerated. The trovafloxacin MICs at which 50 and 90% of 36 Neisseria gonorrhoeae isolates are inhibited were 0.002 and 0.004 mg/liter, respectively (MIC range, <0.0005 to 0.008 mg/liter). These preliminary studies suggest that trovafloxacin is effective for the treatment of uncomplicated gonorrhea at single oral doses as low as 50 mg.