There is still no consensus on which hepatitis B virus (HBV) immunisation option should be adopted in the United Kingdom (UK). This review considers why three recent UK studies on the subject reached different conclusions, and whether they provide sufficient information to base an informed decision on cost-effectiveness grounds. The studies differed in methodology, particularly in the models used to estimate the effectiveness of the competing programmes. This led the authors to draw very different conclusions as to the relative cost-effectiveness of universal infant and selective immunisation, probably because the study that favoured infant immunisation omitted an allowance for the indirect protection afforded to others by immunisation of a proportion of the population. This would lead to the underestimation of the relative effectiveness of a programme targeted at high-risk individuals. Selective vaccination is probably more cost-effective than mass immunisation, but universal immunisation may still be considered a cost-effective option (in addition to selective immunisation) if future health benefits are not discounted (i.e., given a lower value than present ones). If future health benefits are discounted then mass infant immunisation is almost certainly not cost-effective. If selective immunisation is to be adopted, then the current (selective) strategy should be properly implemented, as it appears to have had little impact on HBV infection and disease.