A retrospective population-based case-control study of sexually transmitted urethritis was conducted at a large military base over a 21-month period. During the study, 9,514 patients were seen for sexually transmitted disease. The analysis was restricted to active duty males and showed that Blacks had 14.8 times the incidence rate of gonococcal urethritis (GCU) and 4.7 times the rate of nongonococcal urethritis (NGU) compared to Whites. There were slightly fewer cases of NGU than GCU. A case-control study of active duty soldiers showed that both Black and White circumcised subjects were 1.65 times as likely to have NGU as uncircumcised subjects (95% CI: 1.37-2.00). However, circumcision was not associated with an increased incidence of GCU.