Background and Objectives: Previous studies have shown that self-inserted vaginal tampons can be used to obtain specimens for detection of Neisseria gonorrhoeae. There is a need to expand testing for infection with Chlamydia trachomatis to women who do not undergo regular gynecologic examinations. Goal: To compare self-inserted tampons with clinician-obtained endocervical swabs for collection of samples to be examined for chlamydial infection. Study Design: Women referred because of recently detected untreated chlamydial infection inserted a vaginal tampon. Two endocervical swabs were obtained after the tampon was removed. One swab was cultured for Chlamydia trachomatis. The other swab and the tampon were examined with the Testpack Chlamydia antigen detection test. Results: Sixty-nine women were studied. Chlamydial infection was detected by culture in 75.4%, by Testpack (swab) in 63.8%, and by Testpack (tampon) in 52.2%. Conclusions: Tampon-obtained specimens evaluated in the Testpack Chlamydia test were relatively insensitive. More sensitive tests for the detection of Chlamydia trachomatis infection with self-obtained specimens should be evaluated.