The authors analyzed four hundred fifty-six cases of syphilis reported via a passive disease surveillance system in the Navy and Marine Corps during 1985-1987. The annual incidence of all reported cases significantly increased during this time from approximately 16 out of 100,000 in 1985 to 23 out of 100,000 in 1987. Much of this increase is attributed to concurrent increased rates of primary syphilis and late latent syphilis. Incidence rates for all stages of syphilis combined increased significantly among men and blacks during these years. Cumulatively, most reported patients were male (422, 96.1%), aged 20-24 years (204, 55.1%), E-3 (junior) enlisted pay grade (101, 30.1%), and black (217, 53.8%). Sexual exposures were reported most frequently from the eastern U.S. coast and from western Pacific countries.