The lack of response to hepatitis B vaccination remains a problem for those individuals directly at risk of hepatitis B infection, particularly those who work in the health care industry. The factors associated with non-response to hepatitis B vaccination have been investigated in 86 non-responder health care workers who had received multiple 'S' vaccinations without sustained production of anti-HBs. This group received a recently developed hepatitis B vaccine, Hepagene™, which included proteins derived from the envelope region of HBV, not present in currently licensed vaccines. The pre-S1 and pre-S2 proteins were included in Hepagene™ in order to circumvent anti-HBs non-responsiveness which had previously been demonstrated in the inbred mouse model. The inclusion of these additional proteins in Hepagene™ enabled some seroconversion, from non-responder to responder; however, a proportion of the vaccinees remained non-responders and the reasons for this have been investigated here, with reference to HLA alleles and the demographic predisposition. Here the mechanisms that underlie hepatitis B vaccine non-response have considered the distribution of HLA alleles, age, sex, height and weight in addition to the T-cell responses to Hepagene™ derived antigens.