For the third consecutive year, the incidence of syphilis has substantially increased in Connecticut. We observed how this statewide increase was reflected in patients seen in our outpatient adolescent clinic. All patients presenting to the outpatient adolescent clinic of a major urban medical center had serologic evaluation for syphilis whenever indicated, in addition to routine annual testing. From June 1982 to May 1988, only one case of syphilis (an adolescent female) was diagnosed. However, in the two years from June 1988 to May 1990, 14 cases of syphilis (12 adolescent females, two adolescent males) were diagnosed. Of the female patients, seven of them had secondary syphilis, three had early latent syphilis of less than 1 year's duration, and two had early latent syphilis of greater than 1 year's duration. Their average age was 18.6 years. Seven patients were black, four were Hispanic and one was white. Nine of the 12 had a history of other sexually transmitted diseases (STDs). Five patients admitted to illicit drug use and one to prostitution. Of these 12 patients, nine were tested for the human immunodeficiency virus and the results were negative. We observed an alarming increase in the incidence of syphilis in our adolescent female patients.