In chronic viral hepatitis, liver biopsy is performed to grade and stage liver damage. Liver biopsy samples are usually taken with a needle using a percutaneous procedure. This method produces a core of tissue representing approximately 1/50,000th of the liver mass, which raises concern about how representative a needle biopsy can be. A critical review of the literature reveals methodological limits unacceptable in this era of evidence-based medicine. Integrating earlier experience with more recently produced data indicates that a biopsy sample 2 cm or more in length containing at least 11 complete portal tracts should be reliable for grading and staging chronic viral hepatitis.