Genotyping of Neisseria gonorrhoeae has proved highly discriminatory. It has been used to differentiate between isolates of the same serovar, to determine the genetic relatedness of antibiotic resistant isolates and to identify isolates from sexual contacts. This level of resolution has been possible because Neisseria gonorrhoeae exhibits a high degree of genetic variability. The validity of using any typing technique to study temporal or geographical differences of an organism known to be non-clonal should, however, be carefully considered.