Kaposi sarcoma (KS), an unusual tumor of vascular origin, was one of the first recognized manifestations of AIDS. In the past few years, it has become clear that human herpesvirus-8 (HHV-8) is critical to the development of KS in the setting of immunosuppression, such as that seen with HIV infection. Other genetic and environmental factors may also play a role in the pathogenesis of KS. Of note, several endogenous substances elaborated by HIV-infected cells may promote angiogenesis and the growth of KS. With advances in our understanding of the pathogenesis of this tumor have come novel treatments for KS. Suppression of HIV replication has substantially decreased the incidence of KS in the western world, and treatment directed at angiogenesis or virus-induced tumorigenesis may ultimately lead to more effective control of KS. For most patients, however, standard chemotherapy, radiation therapy, topical therapies, and interferon-alpha remain the mainstays of treatment. In this review, recent advances in our understanding of the pathogenesis of KS are highlighted and a brief overview of current approaches to the treatment of this tumor is provided.