Self-inserted vaginal tampons for the molecular diagnosis of non-ulcerative STIs were evaluated. Cervical and vaginal swabs, tampons and urines were collected from 185 first-time antenatal clinic attendees. Cultures and nucleic acid amplification assays (NAA) were performed. The sensitivity of PCR on tampons for Trichomonas vaginalis was with 94% (CI 85-98%) significantly higher (P<0.001) than culture (50%, CI 38-62%) or urine (53%, CI 41-65%). Neisseria gonorrhoeae culture had a sensitivity of 64% (CI 36-86%), strand displacement assay (SDA) had a sensitivity of 79% (CI 49-94%) using tampon specimens, 57% (CI 30-81%) using endocervical swabs and 43% (CI 19-70%) using urines. There was no difference in sensitivity of SDA for Chlamydia trachomatis using tampon specimens, urine or endocervical swabs. The specificity approached 100% for all assays on all specimens. NAA on tampons for the detection of T. vaginalis, N. gonorrhoeae and C. trachomatis identified more infections than assays on swabs or urines. This reached statistical significance for T. vaginalis only.