Fifteen commercial syphilis kits were assessed against the same moderately sized specimen panel that included 114 serum and plasma specimens from syphilis cases and 249 specimens from unselected blood donors. The 114 specimens from syphilis cases comprised 40 from cases of primary syphilis, 43 from cases of secondary syphilis, 19 from cases of early latent syphilis, and 12 from cases of late latent syphilis. Of the 15 kits, ten were enzyme immunoassays, four were Treponema pallidum haemagglutination assays, and one was a T. pallidum particle agglutination assay. Thirteen of the 15 kits gave final specificities of 100%; the other two kits were repeatedly reactive with one to two specimens. Initial sensitivities ranged from 93.9 to 99.1%. Most variation between kits was observed in results for the groups with untreated primary and treated late latent disease, although the differences were not statistically significant. The comparative data on kit performance derived from this study is useful for examining syphilis testing guidelines and for making informed purchasing decisions.