The recent elucidation of the life cycle and dynamics of the human immunodeficiency virus (HIV) and technological advances in development of the HIV RNA PCR assay for sensitive detection of viral load have revolutionized the diagnosis, management, and treatment of HIV infection. Beginning with initial infection, there is unremitting, high-level viral replication that persists throughout the course of HIV infection. The measure of the amount of virus present in plasma, HIV viral load, is the single most important predictor of HIV progression, the best indicator of immune system decline, and the best guide for initiating and monitoring antiviral treatment. Further, HIV viral load has become the new yardstick against which other markers, including CD4 number, age, chemokine receptor mutations, cytotoxic T-cell responses, and neutralizing antibody titers are assessed. For individuals with haemophilia, additional 'markers' may have significant impact on the outcome of HIV disease. Chronic factor concentrate treatment has led to transfusion-associated hepatitis, co-infection with hepatitis C (HCV), and chronic liver disease. The latter may become accelerated with HIV progression and may lead to hepatotoxicity with antiviral drug therapy. Chronic factor concentrate treatment has also been associated with immunosuppression, including both B- and T-cell immune defects. In HIV(+) haemophilic men, this immune deficit has led to lower CD4 counts with HIV progression and poorer CD4 response to antiviral drugs than in gay men. The underlying haemophilic bleeding tendency may result in significant haemorrhage with HIV-associated immune thrombocytopenia and with protease inhibitor antiretroviral therapy. Although AIDS is the leading cause of death in this group, the reduction in the size of the haemophilia population over the next two centuries is estimated to be small, and survival should improve as better antiviral therapeutics are identified.