The diagnosis of non-Hodgkin's lymphoma with spontaneous acute granulocytic leukemia was confirmed by examination of the patient's bone marrow and peripheral blood specimens at the light and electron microscopic level, and by autopsy findings. Only one previous case of simultaneous non-Hodgkin's lymphoma and acute myelomonocytic leukemia with no prior history of chemotherapy, radiotherapy, or both, has been reported. Although the present patient was given no mutagenic therapy, his chronic exposure to an unknown insecticide may have played a leukemogenic role.