Human herpesvirus 8 (HHV-8) is thought to be essential for the development of all forms of Kaposi's sarcoma (KS). HHV-8 DNA is present virtually in all KS tumor biopsy samples. Genes at both ends of the HHV-8 genome have been shown to vary considerably. Seven major molecular subtypes of HHV-8 were defined based on the amino acid sequence of the open reading frame K1 (ORF-K1), generally known as A, B, C, D, E, F, and Z. Most strains collected worldwide were clustered into two subtypes (A and C). Here, the K1/VR1 region of HHV-8 was amplified by nested PCR in 22 (81.48%) of 27 cases from Xinjiang Uygur Autonomous Region, a province in northwestern China. Phylogenetic analysis on the basis of the K1/VR1 amino acid sequence indicated that the majority of these KS patients were infected by subtype C HHV-8 (n = 18, including 15 belonging to the C2 group), and several by subtype A (n = 4, including 3 being the A1 group). This is the first report of subtype A HHV-8 in China. Furthermore, the correlations between different forms and lesions of KS and different subtypes of HHV-8 were analyzed. The findings showed that subtype A HHV-8 resulted in significantly more frequent mucosal KS lesions than subtype C. However, there was no obvious correlation between different forms of KS and different subtypes of HHV-8.