The co-administration of the tetravalent meningococcal conjugate vaccine, MenACWY-TT, with a licensed hepatitis A and B vaccine, HepA/B (Twinrix (R)), was compared to their separate administration in this open, randomised, controlled study. Healthy subjects 11-17 years of age (n = 611) were randomised (3:1:1) to receive both vaccines, MenACWY-TT alone or HepA/B alone. The co-administration of both vaccines was shown to be non-inferior to their individual administration. At seven months after the first vaccination, 99.4-100% of the subjects who received both vaccines co-administered showed seroprotection against all meningococcal serogroups and at least 99.1% of them were seropositive for hepatitis A and seroprotected against hepatitis B. This study suggests that MenACWY-TT vaccine could be co-administered with HepA/B without adversely impacting the immunogenicity, safety and reactogenicity of either of the vaccines.