Gamma-herpesviruses closely related to the Epstein-Barr virus (EBV) are known to naturally infect Old World non-human primates and are classified in the same lymphocryptovirus (LCV) genera. LCV infecting humans and Old World primates share similar biology, and recent studies have demonstrated that these viruses share a similar repertoire of viral genes. Surprisingly, the latent infection genes associated with cell growth transformation demonstrate the most striking sequence divergence, but the functional mechanisms for these genes are generally well conserved. The recent discovery of LCVs naturally infecting New World primates has rewritten the old paradigm of LCV host range restriction to humans and Old World non-human primates, so that these viruses are more widespread than previously believed. However, the New World LCV genome has significant and interesting differences from EBV and other Old World LCVs despite similar biological properties. Thus, the simian homologues of EBV can provide an important animal model for studying LCV pathogenesis, and the similarities and differences that have evolved among these related viruses can provide a unique perspective towards a better understanding of EBV.