In this study the authors applied a reverse transcription-polymerase chain reaction (RT-PCR) assay to detect hepatitis C virus (HCV) RNA in 15 frozen liver biopsy samples from anti-D-treated patients. They also correlated the presence or absence of HCV RNA in the serum and liver of each patient with their histologic gradings. RNA was extracted from 36 frozen liver biopsy samples. These included 15 liver biopsy samples from patients infected with HCV through contamination of anti-D blood products. Three of these 15 anti-D-treated patients were receiving alpha-interferon treatment at the time of liver biopsy. Nine frozen liver biopsy samples from patients with a history of intravenous drug abuse were included as positive controls. HCV-negative frozen liver biopsy samples from 12 noninfected patients were used as negative controls. RNA was also extracted from six frozen skin biopsy specimens to check for cross-contamination of samples. Eleven of 15 anti-D-treated patients were HCV RNA positive by RT-PCR, with 100% correlation between HCV RNA in the serum and liver. The nine frozen liver biopsy samples from the intravenous drug abuse patients (positive controls) were also RT-PCR positive for HCV RNA. The 12 noninfected samples and the negative control biopsy samples were negative for HCV. Twenty-seven percent of the recombinant immunoblot assay-positive patients were serum and liver HCV RNA negative. HCV-positive patients receiving alpha-interferon therapy at the time of biopsy had cleared the virus from the serum and the liver. There was no correlation between the presence or absence of serum and liver HCV RNA with the histologic grading. This lack of correlation shows clearly the importance of histopathologic evaluation of liver biopsy samples in monitoring HCV-associated liver disease progression. In addition, this finding indicates that one cannot rely only on the presence or absence of HCV RNA in either serum or liver tissue as a parameter in monitoring HCV-associated liver disease progression in this unique cohort of anti-D-treated patients.