Over a 34-month period, 12,647 Papanicolaou smears were obtained from a student health service outpatient gynecologic population at moderate risk of chlamydial infection. We found 287 (2.3%) to have cytologic features suggestive of chlamydial cervicitis. Chlamydia trachomatis was definitely isolated by endocervical culture in only 4.5% of these 287 subjects. Cytologic features suggestive of chlamydial cervicitis were found to be unreliable in diagnosing chlamydial infection.