ObjectiveTo perform a cost-benefit analysis of aChlamydia trachomatisscreening program based on first-void urine testing of asymptomatic women using a polymerase chain reaction (PCR) test.MethodsA decision tree was developed. Selected variables based on assumptions were subjected to sensitivity analyses to make the model accurate and defensible.ResultsScreening for chlamydial infections using the PCR test was shown to be cost-effective even in lowprevalence populations. Compared with a symptom-driven no-screening situation, a universalC trachomatisscreening program using the PCR test would save money, in terms of direct cost, when the baseline prevalence ofC trachomatisinfection exceeds 3.9%.ConclusionCost analyses are still rare among trials that compare pharmacologic or procedural health care interventions. Socioeconomic studies linking secondary prevention ofC trachomatisinfection and infertility and adverse pregnancy outcome are needed to convince public health authorities of the need for and the benefit of such programs.