SummaryThe in vitro susceptibility of 130Neisseria gonorrhoeaestrains isolated in different Belgian * localities in 1980–1981 was determined for penieilline, tetracycline, spectinomycin and thiamphenicol. Among 70 consecutively isolated strains in Antwerp, 5 were producing penicillinase (PPNG). The non-penicillinase producing strains Were sensitive in vitro to the antimicrobials tested. The antimicrobial susceptibility of Belgian gonococcal strains has not changed significantly since 1974 for spectinomycin. In 1981, more strains had a minimal inhibitory concentration (MIC) of penicillin of 0.5 mg/1 or Ilore. The prevalence of gonococcal strains with a MIC of tetracycline of more than 0.5 mg/1 has decreased.