A retrospective study was performed to assess the efficacy and low mucosal toxicity of intracavitary contact X-ray therapy (ICRT), a proposed treatment of small/medium sized lesions of oral HIV-associated Kaposi's sarcoma (HIV-KS). Twenty-six patients with histologically confirmed oral HIV-KS underwent ICRT in the period 1986-1995. No patient received antiblastic or interferon therapy during the radiotherapy or follow-up periods. ICRT was performed according to the usual technical modalities of contact X-ray therapy, but the end of the source of ionizing radiations was introduced into the oral cavity. The total doses administered ranged from 10 to 50 Gy per field, in one or two weekly fractions of 5 Gy each. The follow-up ranged from 1 to 44 months (mean 7.5 months). Complete remission was obtained in 20 cases (76.92%), partial remission in 6 (23.08%) and relapse in one case (3.84%). Pain was relieved in all cases. Mucosal reaction was mild and did not result in any interruption of treatment. Our data suggest that ICRT is an effective and well tolerated treatment. It can be used in the management of oral HIV-KS instead of external radiotherapy, provided that the size and the location of the lesions and the conformation of the palate are suitable to this technique.