In 1981 1180 penicillinase producing strains of Neisseria gonorrhoeae (PPNG) were isolated in the Netherlands, an incidence of approximately 10% of all gonococcal isolates. Determination of the plasmid pattern of 915 of these strains brought to light important shifts of predominant plasmid patterns in a short period of time. Significant differences between the large cities point to local spread of PPNG strains from different origins. The susceptibility of the PPNG strains to clinically relevant antibiotics varied with the plasmid pattern; this stresses the necessity of permanent surveillance of gonococcal infections and of regular evaluation of the recommendations for antimicrobial treatment.