Non-Hodgkin's lymphoma of B-cell type is the second most common neoplasm after Kaposi's sarcoma, among patients with human immunodeficiency virus infection. Most non-HodgkinNon-Hodgkin's lymphomas (NHL) are the second most frequent malignancies in acquired immunodeficiency syndrome (AIDS) patients. More than 9�% of HIV-associated NHL is derived from B cells and the majority is high-grade and extranodal. The digestive tract is one of the most common extranodal primary sites for NHL in AIDS patients, accounting for ��% of all primary extranodal lymphomas 11 . Burkitt's lymphoma (BL) has frequently been reported as a neoplasm in HIV-infected patients. These lymphomas are now better designated as AIDS-related BL 1 .We report a case of primary BL of the duodenum in an AIDS patient. CASE REPORTA �5-year-old man infected with the human immunodeficiency virus (HIV) and hepatitis C virus (HCV) was admitted to our unit for AIDS-related illness with fever (��°C -��.5°C), anorexia, upper abdominal pain, night sweats and weight loss of three months duration. He had no history of AIDS-defining illness and he had never received highly active antiretroviral therapy (HAART). �hysical examination revealed that he had lost approximately 15kg of weight during the last three months prior to admission. Lung and cardiac auscultation were normal. His abdomen was tender, with spontaneous epigastric and right hypochondrium pain that increased during palpation and hepatomegaly (2cm below the right costal margin). He did not present rebound tenderness.The relevant laboratory findings were: hemoglobin 1�.2g/dl; hematocrit ��%; leukocytes 5,���/mm � ; platelets 15�,���/mm � ; lactate dehydrogenase 1,5�5U/l and alkaline phosphatase 2,��5U/l. Liver function, transaminase level, kidney function and coagulation tests were normal. The CD� T cell count was �7 cell/ul and the plasma viral load was ��,12� copies/ml (log 1� �.�). Multiple blood, urine and sputum cultures were all negative.A chest X-ray was normal. Abdominal ultrasound showed hepatomegaly with increased echogenicity, isoechoic periportal