ObjectiveTo detect and quantify HIV-1 in the liverin vivo.Design: Fourteen liver biopsy samples and corresponding blood lymphocytes and monocytes from patients with AIDS were studied for HIV-1 using quantitative polymerase chain reaction (PCR). In addition, expression of HIV-1 antigen and messenger (m) RNA in 10 autopsy liver specimens was examined by immunohistochemistry andin situhybridizationResultsThe amount of HIV-1 DNA in nine liver samples ranged from 850 to 27000 copies per 106cells, with mean and median values of 8150 and 3500 copies per 106cells, respectively. Five other samples had no detectable HIV-1 DNA by PCR. Intracellular expression of HIV-1 antigen and mRNA was also detected in both Kupffer cells and hepatocytes byin situstudies.ConclusionThese findings strongly indicate that HIV-1 could replicate in the liver of a majority of patients with AIDS.