Kaposi's sarcoma is a multicentric malignant neoplasm probably of endothelial origin. Four forms of Kaposi's sarcoma are now recognised. AIDS-Kaposi's sarcoma is the most common malignant neoplasm associated with HIV-infection. About 20% of patients with HIV infection develop Kaposi's sarcoma and half on of them appear oral lesions. The oral mucosa may be the first or the only site of the tumor. In this paper a rare case of oral Kaposi's sarcoma which was the first sign of AIDS in a 43-years old homosexual man is presented.