Urogenital and rectal specimens collected from the "IWantTheKit" Internet-based sexually transmitted infection screening program were evaluated for Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis. Of 881 paired specimens submitted from August 2013 to December 2016, 15.0% (n = 132) tested positive for 1 or more sexually transmitted infections, of which 50.8% (n = 67) were identified exclusively through rectal testing.