A new herpesvirus-like DNA sequence (KSHV) has been recently identified in Kaposi's sarcoma (KS) from patients with AIDS and non-AIDS patients. To verify the specificity of the association of this new viral DNA with KS, a total of 155 cases of benign and malignant vascular neoplasms sharing similar histogenesis of endothelial derivation were analyzed for the presence of this KSHV sequence using the published 330-233 primers by polymerase chain reaction (PCR). The results revealed that all 17 cases of KS, both AIDS and non-AIDS, were positive for this KSHV, whereas the remaining 138 cases of vascular lesions other than KS, including 15 cases of angiosarcoma, showed negative reaction. These results confirm and extend the previous observation that this KSHV sequence is specifically associated with KS and is a reliable diagnostic marker to distinguish KS, particularly at its early stage, from other vascular lesions.