Summary. Treatment with contaminated plasma products before 1990 resulted in extraordinary prevalence rates of human immunodeficiency virus (HIV) and hepatitis B and C viruses (HBV, HCV). In the Second Multicentre Haemophilia Cohort Study (MHCS-II) during 2001–03, 30% of HCV-seropositive survivors had HIV and 4.6% were HBV carriers. Highly active antiretroviral therapy (HAART) radically altered the consequences of HIV/HCV coinfection. Whereas opportunistic infections predominated previously, current major complications are liver failure and bleeding (exacerbated by decreased clotting factor synthesis, hypersplenic thrombocytopenia, and oesophageal varices). Most HIV-positives in MHCS-II were HIV RNA-negative and had > 200 CD4+ cells µL−1, but only 59% were on HAART. With HIV, especially after 41 years of age, liver disease was apparent (jaundice in 5%, ascites 7%, hepatomegaly 9%, splenomegaly 19%). HAART increases survival but may contribute to various comorbidities. Without HIV, sustained HCV clearance is obtained in > 50% with combined pegylated interferons plus ribavirin, but data in haemophilic populations, especially with HIV, are limited. In MHCS-II, HCV RNA negativity was 41% following standard interferon plus ribavirin; among interferon-naïve participants (implying spontaneous HCV clearance), HCV RNA negativity was 12% with and 25% without HIV. Without HIV, spontaneous HCV clearance was much more likely with early age at infection and particularly with recent birth (late 1970s or early 1980s) but not with bleeding propensity or its treatment. Most (72%) participants had received no anti-HCV therapy. Hepatic and haematological conditions are likely to increase during the coming years unless most adult haemophiliacs are successfully treated for HIV, HCV or both.