A 73-year-old man was hospitalized with fever, erythema, generalized superficial lymphadenopathy and marked neutropenia in July 2007. Hematologic examination demonstrated a white blood cell count of 1,400/microl with 0% neutrophils, and 18% abnormal lymphocytes. A bone marrow aspirate showed marked myeloid hypoplasia. A diagnosis of drug-induced agranulocytosis was made. Although neutrophil counts immediately returned to normal levels in response to filgrastim, fever, skin rash and systemic lymphadenopathy were all persistent. He also developed autoimmune hemolytic anemia and a second episode of agranulocytosis. The causative agent of the both episodes of agranulocytosis appeared to be acetaminophen. The histologic picture of a biopsied lymph node showed diffuse infiltration of polymorphous lymphoid cells with clear cytoplasm and proliferation of arborizing capillary vessels. Based on the histologic findings, PCR, and immunohistologic analyses, he was diagnosed with angioimmunoblastic T cell lymphoma (AILT) in leukemic state. The response of the lymphoma to conventional chemotherapy (CHOP and ESHAP) was poor. We next performed an immunomodulatory therapy using cyclosporine A to suppress cytokine production by neoplastic T cells. The treatment resulted in a partial remission of AILT including disappearance of circulating lymphoma cells. To our knowledge, this is the first published report of AILT complicated by drug-induced agranulocytosis.