Behavioural risk factors for HIV/AIDS in Bangladesh were reviewed in a preceding article in this journal. Omitted from that review was a discussion of potential biomedical risk factors including: (i) an unregulated blood supply system in which blood used in transfusions is not screened for HIV and is donated primarily by professional donors: (ii) unsterile injections in non-formal and formal health-care settings; and (iii) a high prevalence in high-risk groups of other sexually transmitted diseases (STDs) which may function as co-factors for HIV transmission, particularly if chronically untreated. Studies elsewhere in the world suggest that the unregulated blood supply system, in particular, poses a serious danger in terms of the spread of the HIV epidemic. While certain socio-cultural factors may be contributing to low levels of HIV in Bangladesh, the prevalence of biomedical and behavioural risk factors suggest the importance of implementing targeted cost-effective interventions now.