Neoplasia may develop in patients with malignant hematologic disorders, during remission after radio and/or chemotherapy. A multifactorial origin related to therapy may be postulated. From 1978 to 1987, among 142 patients with malignant hematologic disorders (Hodgkin lymphoma 33, non-Hodgkin lymphoma 51, Multiple Myeloma 35 and Chronic Myeloid Leukemia 31) we observed 3 patients developing another neoplasia. An additional patient with acute non-lymphatic leukemia had been submitted to chemotherapy for gastric cancer. Four other patients with double neoplasia, one of them a hematologic one, had not been submitted to chemotherapy. The lack of national registries for neoplastic diseases precludes an estimation of the odd ratios involved in our findings.