We used decision analysis to estimate the clinical and economic implications of testing for cervical infection caused by Chlamydia trachomatis in women during routine gynecologic visits. We compared a strategy of no routine testing with a strategy involving the use of routine cultures or the use of less expensive rapid tests for chlamydial infection (the direct fluorescent assay or the enzyme immunoassay). We used different assumptions for the costs and operating characteristics of the diagnostic tests, complications of undetected infection, and the cost of false-positive test results. We found that using one of the rapid tests would reduce overall costs if the prevalence of infection was 7% or greater. The use of routine cultures would reduce costs if the frequency of infection was 14% or greater. We conclude that testing for cervical infection with C. trachomatis in women seeking routine gynecologic care may reduce overall costs. The choice of diagnostic test should depend on the expected prevalence of infection, local cost considerations, and laboratory expertise in the execution of these tests.