In this article we review and discuss the transcripts, protein structure and immune subversive mechanisms of the HCMV viral IL10 (vIL-10) isoforms during productive lytic and latent HCMV infections concentrating on its role in modulating infection in the myeloid lineage and comparing it to the structure and functions of human IL10 and other IL-10 homologs encoded by other herperviruses. Here, IL10 is linked to cytomegalovirus infection.