Kaposi sarcoma (KS)-associated herpesvirus (KSHV) is the most recently discovered human oncogenic herpesvirus. The virus is associated with KS lesions and other human malignancies, including pleural effusion lymphomas and multicentric castleman's disease. The sequence of the viral genome demonstrated that it belongs to the gammaherpesvirus family similar to the Epstein-Barr virus, the only other known human herpesvirus associated with human cancers. Molecular studies have identified a number of viral genes involved in regulation of cell proliferation, gene regulation, chromatin remodeling and apoptosis. KSHV transforms human endothelial cells in vitro with low efficiency and expresses a repertoire of latent genes involved in the establishment of latency. One of these latent proteins, the latency-associated nuclear antigen (LANA) is required for episomal maintenance and tethers the viral genome to the host chromatin. LANA has now been shown to be a multifunctional protein involved in numerous cellular functions including binding to the retinoblastoma protein and p53, regulating cell proliferation and apoptosis.