Auxotyping (growth of cells on chemically defined media) and serotyping (reaction of cells with a defined set of monoclonal antibodies [MAbs]) are the traditional and most widely used methods for the classification of Neisseria gonorrhoeae isolates. As an example, Knapp et al. (1) used the combination of these two typing techniques to study the epidemiology of 489 isolates of N. gonorrhoeae collected over a 3-mo time period. Separately, 11 different auxotypes and 19 different serotypes were found, but when combined, a total of 57 auxotype/serotype classes were identified. Although this system was and still is very useful for epidemiological studies, some laboratories felt more comfortable using molecular techniques to classify their gonococcal isolates.