Vaginal wet smear, endocervical swab test, gynecologic examination, and history were investigated in 148 healthy female adolescents. Cultures for Chlamydia trachomatis were obtained from all patients. The overall prevalence was 19/148 (13%). No significant correlation was found between chlamydia infection and any of the parameters investigated in the wet smear. Results of swab test or history showed no discrimination between young women with cultures positive for C. trachomatis and those with cultures negative for C. trachomatis. Chlamydia was found in 32% of patients when the gynecologic examination showed signs of infection and in 10% when no signs of infection were seen (p less than 0.025). Thirteen of the 19 (70%) adolescents with chlamydia infections had no signs of infection. We conclude that neither swab test, vaginal wet smear, nor the history of the patient can give conclusive evidence of a chlamydial infection. Detection of C. trachomatis in this population can be done only by culture or other specific methods.