During the late 1980s and early 1990s, King County, Washington (1998 population: 1.6 million), experienced a substantial epidemic of infectious syphilis (i.e., primary, secondary, and early latent). Subsequently, reported cases of infectious syphilis declined to six cases in 1995 and one in 1996; five of the 1995 cases and the case in 1996 were believed to have been acquired outside King County. However, in 1997, sustained spread of syphilis was reestablished in King County. To determine whether this reemergence was associated with changes in the epidemiology of other sexually transmitted diseases (STDs), Public Health-Seattle and King County (PHSKC) analyzed notifiable STD data for 1997-1999. This report summarizes the results of this analysis, which indicate that infectious syphilis among men who have sex with men (MSM) in King County increased to 46 cases during January-June 1999, and chlamydia and gonorrhea also increased among MSM attending public health clinics.