Background: Human herpesvirus 8(HHV8) has previously been shown to be associated with Kaposi's sarcoma (KS) skin lesions in HIV-positive and negative patients. This study was designed to test, on a microscopic level, using the microdissection technique in frozen and formalin-fixed tissue, whether HHV8 DNA is specific to the KS lesion. Methods and Results: Thirty-seven evaluable KS lesions were microdissected and DNA extracted, and HHV8-specific polymerase chain reaction (PCR) was performed. All of the KS lesions showed a PCR product; none of the microscopically adjacent normal tissue samples showed a PCR product. One of the PCR products was sequenced, confirming the presence of HHV8 DNA. Conclusions: HHV8 was shown to be specific to the KS lesion at the microscopic level.