Bone marrow cells from a patient with refractory anemia with ringed sideroblasts were studied cytogenetically. All metaphases analyzed revealed an abnormal karyotype with complex defects. The most prominent defect consisted of a rearrangement of the short arm of chromosome 6. Until now, 6p rearrangements have been preferentially observed in myelodysplastic patients with a history of previous exposure to toxic products such as alkylating agents or environmental factors of occupational origin. Although our patient was not exposed to alkylating agents, for about 20 years he has regularly consumed important quantities of analgesics, tranquilizers, and nonsteroidal antiinflammatory drugs. The eventual relationship between sideroblastic anemia and drug abuse, as well as the existence of chromosome sites preferentially rearranged in the bone marrow cells of myelodysplastic patients, are discussed.