Liver biopsy (n = 35) and autopsy (n = 71) specimens from HIV infected HCV-positive and HCV-negative haemophiliacs and non-haemophiliacs and liver biopsies (n = 33) from HIV-negative HCV-infected haemophiliacs and non-haemophiliacs were studied by histo- and immunohistochemistry to investigate the influence of HIV-coinfection on chronic C hepatitis (> 10 years duration). Almost all HIV-infected patients had a CD4 cell counts < 200/microns3. In biopsies and autopsies HCV-infection lead to stronger portal, periportal and lobular inflammatory changes independent from HIV-infection and haemophilia. However, HIV-infected patients with HCV-coinfection showed much more granulocytic infiltrates, particularly in the small bile ducts. In biopsies and autopsies HCV infection was associated with a stronger (centrilobular) fibrosis, particularly in HIV-positive haemophiliacs, and significantly stronger compared to HCV-negative patients. In the autopsy group half of the HIV-infected and HCV-positive haemophiliacs (n = 20) had developed posthepatitic liver cirrhosis due to C hepatitis, contrasted by two liver cirrhosis in HCV-infected non-haemophiliacs (n = 6) due to chronic B and C hepatitis and chronic alcohol abuse; no liver cirrhosis was observed in HIV-positive HCV-negative non-haemophiliacs (n = 45). Cholestasis and mild granulocytic cholangiolitis was a predominant feature in HIV/HCV-coinfection and similar distributed in haemophiliacs and non-haemophiliacs. The findings are suggestive that HIV-coinfection aggravates the course of a preceding hepatitis C virus infection, by a more granulocytic inflammatory infiltrate, stronger (centrilobular) fibrosis followed by a high incidence of posthepatitic cirrhosis--particularly in multitransfused haemophiliacs--and by cholestatic hepatopathy.