Of 50 blood culture sets, 20 Bacto (Difco Laboratories, Detroit, Mich.), 20 Septi-Chek (Hoffmann-La Roche, Inc., Nutley, N.J.), and 10 BACTEC 6B and 7D (Johnston Laboratories, Inc., Towson, Md.) sets were inoculated with Campylobacter pylori and fresh human blood. None of the 50 blood cultures produced any detectable growth. Current commercial blood culture systems may be inadequate for the detection of C. pylori bacteremia.