Chlamydia trachomatis genital infections often go unrecognized where specific culture diagnosis is not easily accessible. We studied the prevalence and clinical correlates of C trachomatis in a geographically isolated Alaskan Eskimo population with a high rate of gonorrhea but for whom specific chlamydial diagnosis had never been available. Using a direct immunofluorescent stain of endocervical secretions, we screened 493 women (52% of all women of reproductive age) when they presented to regional health facilities during the year-long study period. Chlamydia trachomatis was identified in 23% (114/493), including 39% (31/80) of teenagers, 30% (34/115) of prenatal patients, 47% (7/15) of pregnant teens, and 40% (8/19) of women with pelvic inflammatory disease. Genital symptoms, clinical signs, and the presence of concomitant gonorrhea were ineffective means of identifying chlamydial infection. This study demonstrates the successful use, and public health importance, of nonculture direct testing to document the unrecognized high prevalence of C trachomatis infection where culture diagnosis is not available.