Two human herpesvirus 6 (HHV-6) open reading frames were identified with significant amino acid similarity to UL86 (major capsid protein, MCP) and UL85 of human cytomegalovirus (HCMV) in human herpesvirus 7 (HHV-7) genes. The predicted lengths of the complete HHV-7 MCP and the HCMV-UL85 open reading frames were 1344 and 293 amino acids with estimated molecular weights of approximately 153 and 33 kDa, respectively. Computer analysis showed that the amino acid of HHV-7 MCP was 61% identical to the MCP of HHV-6 variants A and B, 28% to HCMV. These results suggest that HHV-7 is more closely related to HHV-6 than to HCMV.