This study examines the relationship between oral contraceptive use and Chlamydia trachomatis cervical infection in women less than 19 years of age. The clinical and epidemiologic data of 73 (19.4% prevalence rate) girls with chlamydial infection were analyzed, with special attention given to contraceptive use. The findings were compared with data from 303 girls who were chlamydia negative to assess the relationship between oral contraceptive use and C. trachomatis infection. Use of an oral contraceptive for 6 months or longer was associated with chlamydial infection (p = 0.005; odds ratio = 2.41; 95% confidence interval 1.53-3.29). Oral contraceptive use was not associated with an increased rate of Neisseria gonorrhoeae or Trichomonas vaginalis infection. Association of oral contraceptive use with chlamydial infection remained significant after adjustments were made for confounding variables in a logistic regression process (p = 0.013). This study suggests that oral contraceptive use may promote chlamydial infection of the cervix or enhance the detection of the C. trachomatis from the cervix in this population.