We report a patient with adult T-cell leukemia (ATL) complicated with intestinal tuberculosis. A 57-year old man was admitted to our hospital because of fever and dyspnea. He was diagnosed as ATL by leukocytosis [leukocyte count 18,200/microliters with 56% of abnormal lymphocytes which express CD4(+) and CD25(+)] and seropositive result of anti-HTLV-1 antibody. Combination chemotherapy for ATL improved his serum LDH level and peripheral lymph nodes, but fever was still persistent. He had an emergency operation because of perforation of the cecum during the chemotherapy. Histological examination of the resected cecum revealed caseous necrosis and numerous mycobacterium, which induced a diagnosis of intestinal tuberculosis. Although there have been several reports on pulmonary tuberculosis in patients with ATL, this is the first report of intestinal tuberculosis in ATL as far as we know. We conclude that if the patients with ATL have persistent fever of unknown origin, we should take account of intestinal tuberculosis as one of differential diagnosis.