Human herpesvirus-8 (HHV-8), a recently discovered oncogenic human virus, is consistently associated with Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD). These disorders occur more frequently, but not exclusively, in human immunodeficiency virus (HIV)-infected individuals, and exhibit more aggressive clinical courses when developing in the setting of acquired immunodeficiency syndrome (AIDS). One of the most intriguing aspects of HHV-8-related disorders is the involvement of numerous growth factors in their pathogenesis. This review will focus on several HHV-8 gene products that exhibit proinflammatory and proangiogenic activities or act as transcriptional activators of cellular cytokines that are involved in the pathogenesis of HHV-8-related disorders.