The polymerase chain reaction (PCR) is a molecular diagnostic technique that has been applied to many infectious processes. Stained and unstained Tzanck smears, vesicle fluid swabs, and crusts have all been used as the source for template DNA for the PCR to document evidence of herpes simplex virus (HSV) and varicella-zoster virus (VZV) infection. Thirty-five cases with histologic evidence of acute herpesvirus infection were retrieved from archival tissue blocks which were up to 5 years old. Paraffin and hematoxylin and eosin stained tissue sections obtained from routinely prepared glass slides were then examined for herpesvirus DNA using the PCR.PCR detected herpesvirus DNA from 34 (97.1%) of 35 paraffin tissues samples. HSV and VZV DNA were detected in 8 and 26 of these cases respectively. From stained tissues samples, PCR detected herpesvirus DNA sequences in 16 (45.7%) of 35 cases. Herpesvirus DNA was isolated from paraffin-tissue sections obtained from archival tissue blocks that were up to 5 years old.PCR can detect herpesvirus DNA in extremely high yield from unstained paraffin-embedded tissues with histologic evidence of acute herpesvirus infection that are up to 5 years old. Herpesvirus DNA can also be identified in approximately 50% of these cases from hematoxylin and eosin stained tissue sections obtained from routinely prepared glass slides.