The auxotype/serovar (A/S) class of 489 isolates of Neisseria gonorrhoeae were determined and 425 isolates from 390 consecutive patients with gonorrhea who attended the Sexually Transmitted Diseases Clinic at Harborview Medical Center in Seattle during the first three months of 1985 were analyzed. Patients included 123 women, 187 heterosexual men, and 80 homosexual men. A total of 57 A/S classes of N. gonorrhoeae were identified during this study. For the first eight weeks, between three and seven new A/S classes were identified each week. The number of new A/S classes encountered in this community declined subsequently, and leveled off at about zero to two new A/S classes introduced per week. Two A/S classes were limited almost solely to homosexual men, one group of related classes was limited to heterosexual patients, and one class was initially limited largely to heterosexual men, possibly because of spread from a prostitute. The results show that the A/S classification system can be used in combination with epidemiologic data for tracing the introduction and spread of gonoccocal strains and their eventual elimination from a community. A/S classification can be used to study the clinical epidemiology of gonorrhea and may facilitate evaluation of strategies for control of gonorrhea. © 1987 American Sexually Transmitted Diseases Association.