144 strains each of penicillinase producing (PPNG) and non-penicillinase producing (NPPNG) Neisseria gonorrhoeae were tested for susceptibility to pefloxacin. All isolates but one (99.65%) were susceptible to 0.06 mg/l. No significant difference was detected between the minimum inhibitory concentrations (MICs) of PPNG and NPPNG strains. The MIC50 and MIC90 of both types of strains were 0.015 mg/l and 0.06 mg/l respectively. Since pefloxacin was more effective than norfloxacin and rosoxacin against PPNG as well as NPPNG, it should prove useful in the therapy of gonorrhoea.