Kaposi's sarcoma (KS) is an important mucocutaneous neoplasm with four well-known clinicopathologic types. Involvement of the oral cavity may be seen in all variants but is most common with AIDS-KS. The latter may signal undiagnosed HIV infection. Its common association with disseminated disease has potentially important diagnostic and therapeutic implications. Oral KS (OKS) most often affects the hard and soft palate, gingiva, and dorsal tongue with plaques or tumors of coloration ranging from non-pigmented to brownish-red or violaceous. Its involvement ranges from an incidental finding to proliferative tumor formation that interferes with mastication. OKS needs to be distinguished clinically from other entities, including pyogenic granuloma, hemangioma, bacillary angiomatosis, and gingival enlargement caused by cyclosporine, a drug frequently used in recipients of organ transplantation. KS may flare as part of the immune reconstitution inflammatory syndrome in HIV patients or develop in the context of iatrogenic immunosuppression. Management, which may depend upon a variety of factors including the clinicopathologic type of KS and results of staging, ranges from no treatment to local measures such as intralesional vinblastine or systemic administration of cytotoxic chemotherapy for disseminated disease. Modification of immunosuppressive regimens often helps control post-transplant OKS but enhances the risk of graft rejection. Screening donors and recipients of organ transplants for HHV-8, with prophylactic treatment if infected as well as institution of sirolimus early after transplantation, are proposed strategies aimed at preventing post-transplant OKS.